Primary, Secondary Prevention and Cancer Detection: Situation, Opportunities and Challenges

With the increasing incidence of cancer in Latin America, the morbidity, mortality, and associated costs are mainly attributed to cancer in the advanced stage. Primary prevention, early detection and diagnosis, and timely and optimal treatment are leading public health priorities. In this section, we focus on current cancer prevention and detection strategies, particularly for cancers accessible to research and early detection; We also describe the challenges that arise in creating optimal cancer prevention and detection programs throughout Latin America and the Caribbean.

Primary prevention

The most profitable strategy for cancer control is through primary prevention, by reducing the main risk factors and protecting the health and well-being of the population.

The main risk factors that can be acted on for cancer are tobacco use, excessive alcohol consumption and obesity. In addition, some types of cancer are related to infectious agents, such as the hepatitis B virus (HBV), HIV, HPV, and H pylori. Indoor and ambient air pollution (particulate air pollution, household air pollution from solid fuels) in the home, workplace, and community are other preventable causes of cancer. The International Agency for Research on Cancer has identified 415 known or suspected carcinogens; ((Clapp RW, Jacobs MM, Loechler EL. Environmental and occupational causes of cancer: new evidence 2005–2007. Rev Environ Health 2008; 23: 1– 37.)) Here, we focus on the risk factors associated with frequent cancers.

Tobacco

Tobacco use is the single most important risk factor for cancer, contributing to 26% of all cancer deaths and 84% of lung cancer deaths in Latin America, a problem that is progressively worsening. In addition to lung cancer, tobacco use has been linked to an increased risk of cancer of the mouth, larynx, pharynx, esophagus, liver, pancreas, stomach, kidney, bladder, cervix, bowel cancer, and possibly breast cancer. . ((WHO. WHO Global Report: mortality attributable to tobacco. Geneva: World Health Organization, 2012))

There are around 145 million smokers aged 15 and over in Latin America. Adult tobacco use varies widely, from 35% in Chile and 30% in Bolivia, to 11% in Panama and 11.7% in El Salvador (Table 7). The highest rates of smoking occur in cities (up to 45% in Santiago, Chile, and 39% in Buenos Aires, Argentina) and contribute greatly to passive exposure to tobacco smoke. ((Muller F, Wehbe L. Smoking and smoking cessation in Latin America: a review of the current situation and available treatments. Int J Chron Obstruct Pulmon Dis 2008; 3: 285–93.)) ((Champagne BM, Sebrie EM, Schargrodsky H, Pramparo P, Boissonnet C, Wilson E. Tobacco smoking in seven Latin American cities: the CARMELA study. Tob Control 2010; 19: 457–62.)) Although tobacco use is higher among men, the rates are increasing rapidly among women; in Santiago and Buenos Aires smoking rates are similar for men and women. ((Champagne BM, Sebrie EM, Schargrodsky H, Pramparo P, Boissonnet C, Wilson E. Tobacco smoking in seven Latin American cities: the CARMELA study. Tob Control 2010; 19: 457–62.)) Chile, Argentina and Uruguay have the highest rates of female smoking in the region (Table 7). In general, Latin America presents the smallest difference between the genders for smoking worldwide, with a ratio of 3: 2 men / women in smokers. ((Muller F, Wehbe L. Smoking and smoking cessation in Latin America: a review of the current situation and available treatments. Int J Chron Obstruct Pulmon Dis 2008; 3: 285–93)) The popularity of tobacco use among adolescents it is particularly concerning. In many Latin American countries, smoking rates among 13-15 year olds are now higher than among adults. Current use among adolescent women has exceeded that of men in Argentina, Brazil, Chile, Mexico and Uruguay. Unless these high smoking rates are reduced, cancer death rates will continue to rise. ((Muller F, Wehbe L. Smoking and smoking cessation in Latin America: a review of the current situation and available treatments. Int J Chron Obstruct Pulmon Dis 2008; 3: 285–93))

There are highly effective interventions to reduce tobacco use, and anti-smoking policies offer the best opportunity to decrease cancer mortality. Potential options include tobacco taxes and restrictions on tobacco marketing, and labeling and packaging of tobacco products, as well as restrictions on smoking in public places; These strategies are detailed in the WHO Framework Convention on Tobacco Control, which has been ratified by 28 countries in Latin America. Currently, 12 countries have adopted laws prohibiting smoking in all closed public places and workplaces; 12 others have put in place regulations on the packaging and labeling of tobacco products; and ten countries have introduced bans on tobacco advertising, promotion and sponsorship. Along these same lines, 15 countries now have a tax share of at least 50% of the total price of cigarettes (panel 3). ((WHO Global Report: mortality attributable to tobacco. Geneva: World Health Organization, 2012.)) ((PAHO. Advances in the implementation of the WHO Framework Convention on Tobacco Control: http://new.paho.org/hq/index.php?option=com_content&view=article&id=5723&Itemid=4139&lang=en (accessed Sept 17, 2012).))

Within Latin America, Uruguay is one of the leading countries in terms of tobacco control. In 2006, Uruguay became the first country to adopt a 100% smoke-free policy in public places and workplaces. In addition, when the price of cigarettes increased to $ 4.00 and packaging restrictions were imposed, the rate of adult smokers in Uruguay decreased from 32% in 2005 to 25% in 2011. Among adolescents, consumption also it decreased from 33% in 2005 to 18% in 2011. The frequency of smoking among physicians decreased from 27% to 9%. ((PAHO. CARMEN meeting report.http://new.paho.org/carmen/?Page_id=11 (accessed Sept 17, 2012).)) In Brazil, a national survey on smoking in 2003 showed a decrease in the frequency of smokers and a modest reduction (about two cigarettes a day) in the average number of cigarettes smoked in recent years. ((Monteiro CA, Cavalcante TM, Moura EC, Claro RM, Szwarcwald CL. Population-based evidence of a strong decline in the prevalence of smokers in Brazil (1989–2003). Http://www.who.int/bulletin/volumes/85/7/06-039073/en/index.html (accessed Dec 20, 2012).)) According to the 2010 Global Burden of Disease Study, the burden of disease attributable to tobacco use in Latin America has fallen slightly. ((Lim SS, Vos T, Flaxman AD, et al. A comparative risk assessment of burden of disease and injury attributable to 67 risk factors and risk factor clusters in 21 regions, 1990–2010: a systematic analysis for the Global Burden of Disease Study 2010. Lancet 2012; 380: 2224–60)) These trends may reflect changes in public policy that encourage smoking cessation.

Obesity, diet and physical activity

The relationship of colorectal, kidney, gallbladder, breast, and endometrial cancers to diet, physical activity, and obesity is well established.171 Diets rich in fruits and vegetables, high in fiber, little red meat and processed , and limited alcohol consumption, along with physical activity and maintaining a healthy weight, have been associated with a lower risk of cancer. ((World Cancer Research Fund, American Institute for Cancer Research. Food, nutrition, physical activity and the prevention of cancer: a global perspective. Http://www.dietandcancerreport.org/ (accessed Jan 21, 2013).))

Obesity is a growing problem in Latin America and is the main general risk factor for disease in South America. ((Obesity is a growing problem in Latin America and is the main general risk factor for disease in South America.3 Estimates at the Regional level indicate that around 139 million people (23%) are classified as overweight or are obese.173 Costa Rica, Paraguay, and Venezuela have the highest rates of obesity in adults (BMI ≥30, Table 7.) There are more women who are overweight or obese than men in almost all Latin American countries, but the differences are particularly evident in the Andean region (Ecuador, Bolivia and Peru), where obesity among women is double that of men. Worldwide, the percentage of people who are overweight or obese is expected to increase, and by 2030 , it is expected that 50% of men and 60% of women in Latin America will be overweight or obese.174)) Estimates at the Regional level indicate that around 139 million people (23%) are classified as who are overweight or obese. ((PAHO. Strategy for the prevention and control of noncommunicable diseases.http://new.paho.org/hq/index.Php?Option=com_content&view=article&id=7022&Itemid=39541&lang=en (accessed Aug 21, 2012). )) Costa Rica, Paraguay and Venezuela have the highest rates of obesity in adults (BMI ≥30, table 7). There are more overweight or obese women than men in almost all Latin American countries, but the differences are particularly evident in the Andean region (Ecuador, Bolivia, and Peru), where obesity among women is twice that of men. Globally, the percentage of people who are overweight or obese is projected to increase, and by 2030, 50% of men and 60% of women in Latin America are projected to be overweight or obese. ((Webber L, Kilpi F, Marsh T, Rtveladze K, Brown M, McPherson K. High rates of obesity and non-communicable diseases predicted across Latin America. PLoS One 2012; 7: e39589.))

In children, obesity and overweight rates have reached epidemic proportions, with approximately 30% of school-age children in Colombia, Peru, and Ecuador and more than 40% of children in Mexico presenting with overweight or signs of obesity. ((PAHO. Strategy for the prevention and control of noncommunicable diseases.http://new.paho.org/hq/index.Php?Option=com_content&view=article&id=7022&Itemid=39541&lang=en (accessed Aug 21, 2012). )) This has happened as a result of physical and social environments that favor unhealthy lifestyle habits, including physical inactivity, large portion sizes, and increased consumption of high calorie processed foods and sugary drinks.

Actions can be taken to reverse the current obesity epidemic. According to the WHO summary, public policies and advocacy efforts are important for promoting healthy lifestyle changes and being aware of the problem. ((WHO. From burden to best buys: reducing the economic impact of non-communicable diseases in low- and middle -income countries. Http://www.who.int/nmh/publications/best_buys_summary.pdf (accessed Sept 21, 2012).)) Aruba’s call for concerted action on obesity is one example of a regional initiative in which Latin American health ministers are collaborating to create policies that support a healthy diet and physical exercise. ((Pan American Conference on Obesity. The Aruba declaration (a call for concerted action) on obesity. Http://www.paco.aw/pdf/EN_the_aruba_declaration.pdf (accessed Sept 21, 2012).)) Various countries of The region (Chile, Brazil, Costa Rica, Peru, Ecuador and Mexico) have created, or are developing policies to promote healthy eating, requiring food labeling, regulation of food advertising, and demanding healthy diet options in the schools. ((Pan American Conference on Obesity. The Aruba declaration (a call for concerted action) on obesity. Http://www.paco.aw/pdf/EN_the_ aruba_declaration.pdf (accessed Sept 21, 2012).))

Infectious causes of cancer

A recent analysis estimated that 17% of cancer cases in Latin America (150,000 cases per year) are attributable to infections. ((from Martel C, Ferlay J, Franceschi S, et al. Global burden of cancers attributable to infections in 2008: a review and synthetic analysis. Lancet Oncol 2012; 13: 607–15.)) Viral hepatitis infections are the main cause of liver cancer and represent about 82% of all liver cancers in Latin America. ((de Martel C, Ferlay J, Franceschi S, et al. Global burden of cancers attributable to infections in 2008: a review and synthetic analysis. Lancet Oncol 2012; 13: 607–15.)) Although the higher rates High rates of chronic endemic HBV species are found in the Amazon basin, with the highest rates of liver cancer occurring in Guatemala, Honduras, Ecuador, the Dominican Republic, and Nicaragua. ((Knaul F, Wong R, Arreola-Ornelas H, et al. Household catastrophic health expenditures: a comparative analysis of twelve Latin American and Caribbean Countries. Salud Publica Mex 2011; 53 (suppl 2): ​​85–95)) In these regions, the pathogenesis of hepatocellular carcinoma is not well defined and it is unclear to what extent viral hepatitis infection or exposures to other substances, such as aflatoxins, are contributing to the high incidence. There are data showing that the introduction of the HBV vaccine in 26 Latin American countries from the 1980s to the year 2000 coincided with the decrease in the incidence of liver cancer. ((Chang MH, You SL, Chen CJ, et al. Decreased incidence of hepatocellular carcinoma in hepatitis B vaccinees: a 20-year follow-up study. J Natl Cancer Inst 2009; 101: 1348–55.))

HPV is the leading cause of cervical cancer and contributes to other cancers of the anogenital region (vagina, vulva, penis, and anus), as well as cancers of the oropharynx. Studies show that HPV vaccination is cost-effective for cervical cancer prevention in Latin America. ((Goldie SJ, Diaz M, Constenla D, Alvis N, Andrus JK, Kim SY. Mathematical models of cervical cancer prevention in Latin America and the Caribbean. Vaccine 2008; 26 (suppl 11): 59–72)) Vaccination against HPV was first available in 2006, and at least six countries in the region have introduced the vaccine (Argentina, Colombia, Guyana, Mexico, Panama, and Peru). ((Murillo R, Almonte M, Pereira A, et al. Cervical cancer screening programs in Latin America and the Caribbean. Vaccine 2008; 26 (suppl 11): 37–48.)) The two current vaccines protect against HPV 16 and 18, the two dominant oncogenic types that represent from 38.3% (Bolivia) to 78.2% (Argentina) of cervical cancer cases in Latin America (Table 7). ((WHO / ICO Information Center on Human Papilloma Virus (HPV) and Cervical Cancer. Summary report on the Americas. Http://www. Who.int/hpvcentre/en/ (accessed Jan 12, 2013).)) Vaccination Large-scale it is limited by the price of the vaccine and the logistical challenges to vaccination of the target populations. To avoid vaccination in local health centers, vaccination against HPV in schools is a viable option, as a program in Peru has shown. ((Penny M, Bartolini R, Mosqueira NR, et al. Strategies to vaccinate against cancer of the cervix: feasibility of a school-based HPV vaccination program in Peru. Vaccine 2011; 29: 5022–30.))

H pylori has been associated with gastric cancer, and eradication of H pylori infection reduces the risk of gastric cancer. ((Aneja S, Yu JB. The impact of county-level radiation oncologist density on prostate cancer mortality in the United States. Prostate Cancer Prostatic Dis 2012; 15: 391–96.)) The prevalence rates of H pylori vary between 79 , 4–84.7% in Latin America. ((Aneja S, Yu JB. The impact of county-level radiation oncologist density on prostate cancer mortality in the United States. Prostate Cancer Prostatic Dis 2012; 15: 391–96.)) Eradication programs for the entire population, which Including practical and affordable regimens of antibiotics and proton pump inhibitors, they offer the most direct approach to reduce the consequences of H pylori infection. ((World Cancer Research Fund, American Institute for Cancer Research. Food, nutrition, physical activity and the prevention of cancer: a global perspective. Http://www.dietandcancerreport.org/ (accessed Jan 21, 2013).)) These Programs, particularly among high-risk groups, could be cost-effective in Latin America, where gastric cancer is very common (Figure 1A) .1 So far, no such program has been conducted in the region. ((Unger-Saldana K, Pelaez-Ballestas I, Infante-Castaneda C. Development and validation of a questionnaire to assess delay in treatment for breast cancer. BMC Cancer 2012; 12: 626.))

Human T-cell lymphotropic virus type 1 (HTLV-1) is considered the cause of adult T-cell leukemia / lymphoma. The virus is endemic and has a high frequency in some regions of Latin America (highlands of the Andes , northwest and northern regions of Argentina); This accentuates the need for systematic screening of HTLV in blood banks, at least in high-frequency areas. ((Gotuzzo E, Verdonck K. HTLV-1: clinical impact of a chronic infection. In: Institute of Medicine (US) Forum on Microbial Threats; Knobler SL, O’Connor S, Lemon SM, et al, eds. The infectious etiology of chronic diseases: defining the relationship, enhancing the research, and mitigating the effects: Workshop Summary. Washington, DC: National Academies Press, 2004)) ((Agência Nacional de Vigilância Sanitária. Ministério da Saúde. Pesquisa Clínica. http://www.anvisa.gov.br/medicamentos/pesquisa/index.htm. (accessed Mar 2, 2011).))

Environmental causes of cancer

Exposure to environmental carcinogens in homes, workplaces, and urban and rural settings is prevalent in many regions of Latin America. These potential causes of cancer demand better documentation and research, with the goal of achieving cancer eradication and prevention.

An estimated 3 billion people worldwide cook and heat their homes with fireplaces, including a substantial proportion of the population in Latin America. ((WHO. Indoor air pollution and health. Http://www.who.int/mediacentre/factsheets/fs292/en/index.html (accessed Jan 3, 2013))) Many of these people are poor, living in areas rural or remote, and regularly use biomass substances such as wood, animal manure, and crop residues for heating and cooking. In homes with insufficient ventilation, air pollution from residues of biomass combustion can lead to indoor smoke levels that are 100 times higher than acceptable. ((WHO. Indoor air pollution and health. Http://www.who.int/mediacentre/factsheets/fs292/en/index.html (accessed Jan 3, 2013))) Data from in-vitro and in- vitro models Live provide evidence that wood smoke and wood by-products are carcinogenic and promote tumor growth and progression. ((Liang CK, Quan NY, Cao SR, He XZ, Ma F. Natural inhalation exposure to coal smoke and wood smoke induces lung cancer in mice and rats. Biomed Environ Sci 1988; 1: 42–50.)) ((Danielsen PH, Loft S, Kocbach A, Schwarze PE, Moller P. Oxidative damage to DNA and repair induced by Norwegian wood smoke particles in human A549 and THP-1 cell lines. Mutat Res 2009; 674: 116–22)) There may also be an association between exposure to wood smoke and non-small cell lung cancer (CNMP) with epidermal growth factor (EGFR) mutation. A study conducted in Mexico showed that exposure to wood smoke was associated with lung adenocarcinoma in nonsmoking women, ((Hernandez-Garduno E, Brauer M, Perez-Neria J, Vedal S. Wood smoke exposure and lung adenocarcinoma in non -smoking Mexican women. Int J Tuberc Lung Dis 2004; 8: 377–83.)) and researchers suggest that exposure to wood smoke may explain the high rates of EGFR-mutated lung cancer in some regions of Latin America . ((Arrieta O, Rios Trejo MA, Michel RM. Wood-smoke exposure as a response and survival predictor in erlotinib-treated nonsmall cell lung cancer patients. J Thorac Oncol 2009; 4: 1043.)) ((Arrieta O, Martinez- Barrera L, Trevino S, et al. Wood-smoke exposure as a response and survival predictor in erlotinib-treated non-small cell lung cancer patients: an open label phase II study. J Thorac Oncol 2008; 3: 887–93.) ) This association requires further research, as it could explain the high rates of EGFR-mutated lung cancer in Latin America, particularly among women, who are more exposed to stove smoke than men. Studies in Honduras and Colombia provide evidence that exposure to wood smoke increases the risk of cervical cancer and invasive cervical cancer. ((Ferrera A, Velema JP, Figueroa M, et al. Co-factors related to the causal relationship between human papillomavirus and invasive cervical cancer in Honduras. Int J Epidemiol 2000; 29: 817–25)) ((Sierra-Torres CH , Arboleda-Moreno YY, Orejuela-Aristizabal L. Exposure to wood smoke, HPV infection, and genetic susceptibility for cervical neoplasia among women in Colombia. Environ Mol Mutagen 2006; 47: 553–61.)) The organization Sembrando has worked until moment with more than 92,000 families in the Andes of Peru to provide clean kitchens in an effort to reduce indoor contamination in the home. ((Bodereau PN. Peruvian highlands, fume-free. Science 2011; 334: 157))

Exposure to other environmental carcinogens (eg, pesticides and industrial waste), and their role in cancer incidence in Latin America, merit further investigation. High concentrations of arsenic have been detected in drinking water in some areas of northern Chile and in the province of Córdoba in Argentina, and have been linked to bladder and lung cancer in nonsmokers. ((Fernandez MI, Lopez JF, Vivaldi B, Coz F. Long-term impact of arsenic in drinking water on bladder cancer health care and mortality rates 20 years after end of exposure. J Urol 2012; 187: 856–61.)) ((Martinez VD, Vucic EA, Lam S, Lam WL. Arsenic and lung cancer in never-smokers: lessons from Chile. Am J Respir Crit Care Med 2012; 185: 1131–32.)) Lung cancer has been described Among coal miners in Brazil, 192 and higher rates of malignant tumors have been reported in populations living near mines in Ecuador. ((Hurtig AK, San Sebastian M. Geographical differences in cancer incidence in the Amazon basin of Ecuador in relation to residence near oil fields. Int J Epidemiol 2002; 31: 1021–27.)) Exposure to pesticides also increases the risk of cancer and has been linked to brain and esophageal cancer in Brazil. ((Miranda-Filho AL, Monteiro GT, Meyer A. Brain cancer mortality among farm workers of the State of Rio de Janeiro, Brazil: a population-based case-control study, 1996–2005. Int J Hyg Environ Health 2012; 215 : 496–501.)) In Bolivian farmers, genetic abnormalities were attributed to exposure to pesticides. ((Jors E, Gonzales AR, Ascarrunz ME, et al. Genetic alterations in pesticide exposed Bolivian farmers: an evaluation by analysis of chromosomal aberrations and the comet assay. Biomark Insights 2007; 2: 439–45.)) A study conducted in Brazil found correlations between national sales of pesticides and prostate cancer, soft tissue, lip, esophagus, and pancreatic cancer, and mortality from leukemia in men. ((Chrisman Jde R, Koifman S, de Novaes Sarcinelli P, Moreira JC, Koifman RJ, Meyer A. Pesticide sales and adult male cancer mortality in Brazil. Int J Hyg Environ Health 2009; 212: 310–21.)) Finally The role of exposure to nitrates or nitrites and the incidence of gastric cancer is worth investigating, taking into account the high rates of gastric cancer in Latin America and the evidence from Chile that suggests causality. ((Zaldivar R, Robinson H. Epidemiological investigation on stomach cancer mortality in Chileans: association with nitrate fertilizer. Z Krebsforsch Klin Onkol Cancer Res Clin Oncol 1973; 80: 289–95.)) The collaborative agreements of the research work between the WHO centers in Italy and Mexico are promoting research on the health consequences of environmental exposure; the centers plan to focus on populations in Mexico who live in mining areas, live near garbage dumps, or work in brick factories. ((Alegria-Torres J, Baccarelli A. Collaboration between centers of the World Health Organization. Italy supports a Mexican university. Med Lav 2010; 101: 453–57)) Adequate control and monitoring of nuclear and radioactive waste is also important to avoid nuclear incidents. In September 1987, a radiation therapy source was stolen for use as scrap metal from an abandoned hospital in Goiânia, Brazil, resulting in accidental contamination of the region. Four people died from acute radiation toxicity, about 130,000 people went to hospital emergency rooms, and more than 250 people had measurable exposure to radioactive cesium.

Secondary prevention: detection and timely diagnosis

Secondary prevention, or interruption of the disease process at an early stage and with better possibilities of treatment, is a crucial strategy to ease the burden of cancer. Secondary prevention can be accomplished by selecting asymptomatic individuals where there is a reasonable time lag between disease onset and clinical progression and an affordable, accurate, and tolerable examination. ((IARC Working Group on the Evaluation of Cancer-Preventive Strategies. IARC handbooks of cancer prevention: breast cancer screening. Lyon: International Agency for Research on Cancer, 2002.)) However, some screening methods have been shown to be of great value in high-income countries simply cannot be applied in resource-limited settings

Breast cancer

Breast cancer is the most common cause of cancer and the leading cause of cancer mortality in women in Latin America. In the past two decades, mortality from breast cancer in developed countries has decreased, mainly due to mammography detection and timely treatment of breast cancer; ((Peto R, Boreham J, Clarke M, Davies C, Beral V. UK and USA breast cancer deaths down 25% in year 2000 at ages 20–69 years. Lancet 2000; 355: 1822.)) Screening mammography decreases breast cancer mortality by 20–30%, ((Nystrom L, Rutqvist LE, Wall S, et al. Breast cancer screening with mammography: overview of Swedish randomized trials. Lancet 1993; 341: 973–78.)) obtaining the greatest benefit in older women. ((Nystrom L, Rutqvist LE, Wall S, et al. Breast cancer screening with mammography: overview of Swedish randomized trials. Lancet 1993; 341: 973–78.)) ((Kerlikowske K, Grady D, Rubin SM, Sandrock C , Ernster VL. Efficacy of screening mammography: a meta-analysis. JAMA 1995; 273: 149–54.)) In contrast, in Latin America, mortality from breast cancer has increased in the last two decades, and the survival of Breast cancer is, on average, 20% lower than in the US and Western Europe. ((Schwartsmann G. Breast cancer in South America: challenges to improve early detection and medical management of a public health problem. J Clin Oncol 2001; 19 (suppl 18): 118–24)) High mortality rates from breast cancer they can be attributed to being in an advanced stage at the time of diagnosis; only 5–10% of new diagnoses are made in phase I of the disease. The distribution of the disease in early and advanced phase varies regionally within each country, ((Mohar A, Bargallo E, Ramirez MT, Lara F, Beltran-Ortega A. Available resources for the treatment of breast cancer in Mexico. Salud Publica Mex 2009; 51 (suppl 2): ​​263–69)) ((Ministry of Health (MINSAL). National Breast Cancer Program. International Breast Cancer Seminar; Rio de Janeiro, Brazil; April 17 and 18 2009. http://bvsms.saude.gov.br/bvs/palestras/cancer/programa_nacional_cancer_mama_chile (accessed Aug 21, 2012). )) and differs between public and private hospitals, which could be due to socioeconomic factors. ((Instituto Nacional de Cancerologia. Statistical Yearbook 2006, Bogotá, INC, 2007. http://www.cancer.gov.co/contener/contener.Aspx?CatID=437&conID=747 (accessed Aug 20, 2012).)) ((Simon SD, Bines J, Barrios CH, et al. Clinical characteristics and outcome of treatment of Brazilian women with breast cancer treated at public and private institutions — the AMAZONE project of the Brazilian breast cancer study group (GBECAM). San Antonio Breast Cancer Symposium 2009; San Antonio, TX, USA; Dec 11, 2009. Abstr 3082.)) The Amazón study from Brazil showed that women receiving treatment in public institutions have a disease in a more advanced stage at the time of diagnosis. The researchers proposed that high detection rates in the private sector, compared to low rates in the public sector, could be explained in part by differences in the stage of the cancer.

Several steps have been taken in Latin America to improve early detection of breast cancer, including guideline development, provider training, community education, and mammography quality assurance programs. Many countries in the region have national recommendations for the detection of breast cancer (panel 4). ((Gonzalez-Robledo LM, Gonzalez-Robledo MC, Nigenda G, Lopez-Carrillo L. Government actions for the early detection of breast cancer in Latin America. Future challenges. Salud Publica Mex 2010; 52: 533–43 (in Spanish) .)) Participation rates for breast cancer screening are low in many Latin American countries, with only 20% of the eligible population accessing it (ranging from 5% to 75%) ((Passman LJ, Farias AM, Tomazelli JG, et al. SISMAMA— implementation of an information system for breast cancer early detection programs in Brazil. Breast 2011; 20 (suppl 2): ​​35–39.)) ((Klabunde CN, Sancho-Garnier H, Taplin S, et al. Quality assurance in follow-up and initial treatment for screening mammography programs in 22 countries. Int J Qual Health Care 2002; 14: 449–61.)) Since the data on women who are Under examination through the private system, these figures may underestimate the total number of women examined. However, screening mammography rates are well below the WHO recommended 70% coverage to reduce breast cancer mortality. ((IARC Working Group on the Evaluation of Cancer-Preventive Strategies. IARC handbooks of cancer prevention: breast cancer screening. Lyon: International Agency for Research on Cancer, 2002.)) With such a low number of women undergoing periodic mammograms in Latin America The ultimate goal of the review to reduce overall breast cancer mortality cannot be achieved with current mammography programs. Recognizing this, a pilot project has been launched in Colombia to evaluate the timely detection of breast cancer. The study includes healthy, asymptomatic women ages 50–69, who attend health services for some medical reason and are assigned to an official mammography program that includes mammography plus clinical breast examination, compared to a control group similar in age to that proactive screening is not offered. ((Murillo R, Diaz S, Sanchez O, et al. Pilot implementation of breast cancer early detection programs in Colombia. Breast Care (Basel) 2008; 3: 29–32.)) The objectives are: to estimate the effect of the guidelines from the National Cancer Institute of Canada on reducing the degree or stage of breast cancer, the effect of early detection during mammography and breast screening (i.e., number of screenings), and costs for implementing Timely programs in the Colombian health system.

The structures of the health system have been identified as the main obstacles to the success of breast cancer screening. In some regions of Latin America, mammography equipment is scarce and needs repair in up to 20% of cases. ((Pan American Health Organization. Breast cancer in Argentina: organization, coverage and quality of prevention and control actions. Http://www.msal.gov.ar/inc/descargas/Publicaciones/cancer_de_mama.pdf (accessed Sept 20, 2012).)) There is often an uneven distribution of equipment within a country, and many women in remote areas do not have access to screening facilities. ((Brazilian Institute of Geography and Statistics. 2010 population census. Http://www.ibge.gov.br/english/estatistica/populacao/censo2010/default.shtm (accessed Aug 20, 2012).)) ((Ministério da Saúde.HIS sufficient mammography items, more regional concentration and lower product são entraves. http://portal.saude.gov.br/portal/aplicacoes/noticias/default.Cfm?Pg=dspDetalheNoticia&id_area=124&CO_NOTICIA=12810 (accessed Aug 22, Therefore, in many regions of Latin America where women are diagnosed with advanced-stage breast cancer and resources are limited, mammography may not be feasible. Conversely, a decrease in the clinical stage could be achieved through screening with clinical breast exams and education, along with increased availability of primary care. Several initiatives are underway to test community-based models to extend these screening services to women in rural areas. ((Murillo R, Diaz S, Sanchez O, et al. Pilot implementation of breast cancer early detection programs in Colombia. Breast Care (Basel) 2008; 3: 29–32))) ((PATH. Community-based program for breast health , Peru. Http://sites.path.org/rh/files/2012/06/PATH_Breast_cancer_proj_Peru_2012.pdf (accessed Sept 21, 2012).)) A pilot project is being implemented in La Libertad, northern Peru , where community workers teach women the physical signs of breast cancer, and trained midwives perform clinical breast exams. Women with suspicious masses are referred to local hospitals for evaluation and diagnosis of fine needle aspiration biopsies. Women with confirmed cancer are referred to a regional cancer center established in northern Peru (IREN-Norte) for the subsequent treatment of cancer. ((PATH. Community-based program for breast health, Peru. Http://sites.path.org/rh/files/2012/06/PATH_Breast_cancer_proj_ Peru_2012.pdf (accessed Sept 21, 2012).))

In summary, it is crucial to recognize that simply extrapolating the benefits of mammography in developed countries to Latin American countries is not appropriate. The benefits and limitations of screening mammography programs versus efforts to decrease the clinical phase need to be considered. In regions with limited resources for limited health services, the Global Breast Health Initiative (BHGI) has developed evidence-based, financially feasible and culturally appropriate guidelines to improve breast cancer outcomes . In such contexts, BHGI recommends clinical breast examination with or without mammography, along with active awareness programs. ((Anderson BO, Yip CH, Smith RA, et al. Guideline implementation for breast healthcare in low-income and middle-income countries: overview of the Breast Health Global Initiative Global Summit 2007. Cancer 2008; 113 (suppl 8): 2221 –43))

Cervical cancer

Cervical cancer is the leading cause of cancer in ten of the 25 countries in Latin America, and is one of the leading causes of cancer death among women, with 68,220 new cases and 31,712 deaths per year. ((Ferlay J, Shin HR, Bray F, Forman D, Mathers C, Parkin DM. Cancer incidence and mortality worldwide: GLOBOCAN 2008. http://globocan.iarc.fr (accessed Oct 16, 2012).)) Detection Cervical cancer can lead to a substantial reduction in the incidence and mortality from it. In developed countries, cervical cytology reduces cervical cancer mortality by 50%. ((Kitchner HC, Castle PE, Cox JT. Achievements and limitations of cervical cytology screening. Vaccine 2006; 24 (suppl 3): 63–70.)) Therefore, organized screening, with adequate follow-up, has been proposed as the main strategy for the control of the disease in Latin America. ((IARC. Cervix cancer screening. IARC handbook of cancer prevention. Lyon: International Agency for Research on Cancer, 2005.))

Most countries in the region started screening programs between 1985 and 2005. According to a recent survey, at least nine countries report having an organized screening program. ((PAHO. Cervical cancer prevention and control programs: a rapid assessment of 12 countries in Latin America. Http://new.paho.org/hq/index.php?Option=com_content&view=category&layout=blog&id=3595 &Itemid=3637&lang=en (accessed Sept 24, 2012).)) Despite the introduction of screening, cervical cancer death rates have not decreased in most Latin American countries. Mortality rates have decreased in Mexico, Chile, Costa Rica, Colombia and Puerto Rico, but this change is not necessarily related to screening programs at the national level. ((Murillo R, Almonte M, Pereira A, et al. Cervical cancer screening programs in Latin America and the Caribbean. Vaccine 2008; 26 (suppl 11): 37–48.)) The reduction in mortality may instead be due to better coverage and greater precision in the certification of deaths. ((Robles S, White F, and Peruga A. Trends in cervical cancer mortality in the Americas. Pan American Health Organization, Health in the Americas, vol 1 (1998): 171–73.)) Some reports suggest that the quality of Screening tests and access to diagnosis and treatment of positive screening women could be factors in the lack of effect observed with cervical screening in Latin America. ((Murillo R, Almonte M, Pereira A, et al. Cervical cancer screening programs in Latin America and the Caribbean. Vaccine 2008; 26 (suppl 11): 37–48.))

High screening coverage, especially among women in the age group at risk, is essential to reduce mortality from cervical cancer. Cervical cancer screening coverage varies in Latin America, and reports indicate that approximately 50% of women have received a Pap test in the past 3 years. ((PAHO. Cervical cancer prevention and control programs: a rapid assessment of 12 countries in Latin America. Http://new.paho.org/hq/index.php?Option=com_content&view=category&layout=blog&id=3595&Itemid=3637&lang=in (accessed Sept 24, 2012).)) In some countries, such as Puerto Rico and Colombia, detection rates reach 72%. However, many countries have low detection rates, such as Bolivia with 12% and Nicaragua with coverage of only 10%. ((PAHO. Cervical cancer prevention and control programs: a rapid assessment of 12 countries in Latin America. Http://new.paho.org/hq/index.php?Option=com_content&view=category&layout=blog&id=3595&Itemid=3637&lang=en (accessed Sept 24, 2012).)) In Mexico and Paraguay, about 20% of women had never had a Pap test, reaching 50% of women in Guatemala. ((Murillo R, Almonte M, Pereira A, et al. Cervical cancer screening programs in Latin America and the Caribbean. Vaccine 2008; 26 (suppl 11): 37–48.))

Barriers to participation in cervical cancer screening vary in different countries. In Mexico, Bolivia, Ecuador, Venezuela, Peru and El Salvador, the main factors that affect participation are the social and cultural norms that influence women’s notions about health and disease, accessibility to centers for health care and the availability of quality services. ((Bingham A, Bishop A, Coffey P, et al. Factors affecting utilization of cervical cancer prevention services in low-resource settings. Salud Publica Mex 2003; 45 (suppl 3): 408–16))

The quality of the cytological analysis can be suboptimal for diagnostic purposes, even when screening is performed. Some studies suggest that the sensitivity of the Pap test may be as low as 20–25%. ((Nakashima Jde P, Koifman S, Koifman RJ. Cancer mortality trends in Rio Branco, Acre State, Brazil, 1980–2006. Cad Saude Publica 2011; 27: 1165–74 (in Portuguese).)) ((Ferreccio C, Barriga MI, Lagos M, et al. Screening trial of human papillomavirus for early detection of cervical cancer in Santiago, Chile. Int J Cancer 2013; 132: 916–23.)) ((PAHO. Cervical cancer prevention in Peru: lessons learned from the TATI demonstration project. http://www.paho.org/english/ad/dpc/nc/pcc-cc-tati-rpt.htm (accessed Sept 22, 2012).)) Also, when women have results abnormal after the Pap test, there are certain barriers to receiving adequate and timely care. An evaluation in the Peruvian Amazon showed that only 23% of women with positive vaginal smears had received appropriate treatment. ((Gage JC, Ferreccio C, Gonzales M, Arroyo R, Huivin M, Robles SC. Follow-up care of women with an abnormal cytology in a low-resource setting. Cancer Detect Prev 2003; 27: 466–71.)) Most programs exaggerate screening test coverage and outreach, regardless of the health system’s ability to cope with diagnosis and treatment.181 These factors, in addition to low detection rates, are likely Explain why cytology-based screening programs have not reduced cervical cancer mortality in Latin America to the same extent as in developed countries. ((Murillo R, Almonte M, Pereira A, et al. Cervical cancer screening programs in Latin America and the Caribbean. Vaccine 2008; 26 (suppl 11): 37–48.))

To improve detection efficiency (screening) in low-resource settings, new alternatives to cytology-based screening have been introduced, including visual inspection techniques and HPV-DNA testing. ((Murillo R, Almonte M, Pereira A, et al. Cervical cancer screening programs in Latin America and the Caribbean. Vaccine 2008; 26 (suppl 11): 37–48.)) ((Goldie SJ, Gaffikin L, Goldhaber- Fiebert JD, et al. Cost-effectiveness of cervical-cancer screening in five developing countries. N Engl J Med 2005; 353: 2158–68)) Both screening strategies have proven to be cost-effective alternatives to conventional screening programs, based on the screening of three cytologies in environments with few resources. ((Murillo R, Almonte M, Pereira A, et al. Cervical cancer screening programs in Latin America and the Caribbean. Vaccine 2008; 26 (suppl 11): 37–48.)) ((Goldie SJ, Gaffikin L, Goldhaber- Fiebert JD, et al. Cost-effectiveness of cervical-cancer screening in five developing countries. N Engl J Med 2005; 353: 2158–68)) An HPV-DNA test requires less supervision than cytology screening, since it does not It depends on the observer, decreases the frequency of detection intervals, and allows the free collection of vaginal samples. In India, this test has been associated with a significant reduction in the number of advanced cervical cancers and deaths from cervical cancer. ((Sankaranarayanan R, Nene BM, Shastri SS, et al. HPV screening for cervical cancer in rural India. N Engl J Med 2009; 360: 1385–94)) Currently, Mexico, Argentina and Colombia have incorporated DNA tests- HPV in its national programs. ((PAHO. Cervical cancer prevention and control programs: a rapid assessment of 12 countries in Latin America. Http://new.paho.org/hq/index.php?Option=com_content&view=category&layout=blog&id=3595&Itemid=3637&lang=en (accessed Sept 24, 2012).)) ((Ferreccio C, Barriga MI, Lagos M, et al. Screening trial of human papillomavirus for early detection of cervical cancer in Santiago, Chile. Int J Cancer 2013; 132: 916– 23.)) The HPV rapid test (careHPV) is more sensitive than conventional cytology, and can be carried out in laboratories with low resources, since it does not require highly qualified personnel.219 A sample of neck cells is collected. uterine or vaginal and sent to the laboratory for processing, the result is available in 2–4 h. Because this assay has been shown to be simple, fast, accurate, and affordable, it is considered a suitable screening method for low-resource settings. ((Sellors J. HPV in screening and triage: towards an affordable test. HPV Today 2009; 8: 4–5))

Another approach that has been used successfully in settings with limited resources is the “one-visit”, “see and treat” method based on visual inspection with acetic acid (VIA) and cryotherapy of appropriate lesions on the same visit. . In regions with poor access to medical care, VIA is a good way to overcome barriers to diagnosis and treatment of preneoplastic lesions. ((PAHO. Cervical cancer prevention in Peru: lessons learned from the TATI demonstration project. Http://www.paho.org/english/ad/dpc/nc/pcc-cc-tati-rpt.htm (accessed Sept 22, 2012))) ((PAHO. Situation analysis, strategies for cervical cancer screening with visual inspection with acetic acid and treatment with cryotherapy in Latin America and the Caribbean. Washington, DC: Pan American Health Organization, 2012.)) Acetic acid has a higher sensitivity than conventional Pap screening: it is easy to apply, less expensive, does not require laboratory evaluation or by highly qualified medical professionals to carry out the procedure, and allows immediate treatment of precancerous cells. At least eight countries in the region (Bolivia, Colombia, El Salvador, Guatemala, Guyana, Nicaragua, Peru, and Suriname) provide VIA as part of the public health system. ((PAHO. Cervical cancer prevention in Peru: lessons learned from the TATI demonstration project. Http://www.paho.org/english/ad/dpc/nc/pcc-cc-tati-rpt.htm (accessed Sept 22, (2012).)) ((PAHO. Situation analysis, strategies for cervical cancer screening with visual inspection with acetic acid and treatment with cryotherapy in Latin America and the Caribbean. Washington, DC: Pan American Health Organization, 2012.))

Colorectal cancer

Colorectal cancer is the fourth most common cancer in men and the third most common cancer in women in Latin America. ((Ferlay J, Shin HR, Bray F, Forman D, Mathers C, Parkin DM. Cancer incidence and mortality worldwide: GLOBOCAN 2008. http://globocan.iarc.fr (accessed Oct 16, 2012).)) A program Screening with guaiac-based fecal occult blood (PSOH) tests repeated every one to two years, and endoscopic follow-up of positive test results reduces colorectal cancer mortality by 16%. ((Hewitson P, Glasziou P, Irwig L, Towler B, Watson E. Screening for colorectal cancer using the faecal occult blood test, Hemoccult. Cochrane Database Syst Rev 2007; 1: CD001216.)) PSOHs, flexible sigmoidoscopy (with or without PSOH), colonoscopy and double-contrast barium enema are the standard screening methods recommended by the U.S. Preventive Services Task Force. However, because colorectal cancer screening tests can cause harm, are of limited accessibility, are not uniformly accessible to patients, and are all similar in terms of cost-effectiveness, the choice of screening method may be tailored to the private patients or clinical practice settings. ((Pignone M, Rich M, Teutsch SM, Berg AO, Lohr KN. Screening for colorectal cancer in adults at average risk: a summary of the evidence for the US Preventive Services Task Force. Ann Intern Med 2002; 137: 132–41 .))

Although there are national guidelines for the detection of colorectal cancer in most Latin American countries, screening programs are rare. ((Ministry of Health National Presidency. National Cancer Institute. Http://www.msal.gov.ar/inc/noticia_62.php (accessed Aug 20, 2012).))) ((Ministry of Public Health. National Program of cancer control http://www.msal.gov.ar/inc/noticia_62.php (accessed Aug 20, 2012).)) Certain studies from Chile and Uruguay have analyzed the viability of cancer screening using immunohistochemical PSOHs in a average risk population; ((Lopez-Kostner F, Kronber U, Zarate AJ, et al. A screening program for colorectal cancer in Chilean subjects aged fifty years or more. Rev Med Chil 2012; 140: 281–86 (in Spanish))) ((Fenocchi E, Martinez L, Tolve J, et al. Screening for colorectal cancer in Uruguay with an immunochemical faecal occult blood test. Eur J Cancer Prev 2006; 15: 384–90.)) Both projects achieved high compliance rates (77–90 %) and were able to detect early-stage cancers and high-risk adenomas (11–30%). Following the publication of these findings, a nationwide colorectal cancer screening program has begun in Chile that aims to screen 30,000 people a year for the next 5 years. ((Lopez-Kostner F, Kronber U, Zarate AJ, et al. A screening program for colorectal cancer in Chilean subjects aged fifty years or more. Rev Med Chil 2012; 140: 281–86 (in Spanish).)) In Uruguay A similar study is underway to promote screening in normal and high-risk populations. ((National Cancer Institute. International Cancer Screening Network. Http://appliedresearch.cancer.gov/icsn/extlinks.html (accessed Jan 15, 2013).))

Challenges for primary and secondary prevention

There are many reasons why cancer prevention and detection efforts are not more widely available in Latin America, but the main reason is cost. Other socioeconomic factors include individual patient-related financial and cultural barriers, lack of support for adequate patient counseling, a non-ideal healthcare infrastructure, poor laboratory quality, and delays in testing for diagnosis and interventions when cancer is diagnosed. ((Espinosa de Los Monteros K, Gallo LC. The relevance of fatalism in the study of Latinas’ cancer screening behavior: a systematic review of the literature. Int J Behav Med 2011; 18: 310–18.)) ((Unger- Saldaña K, Infante-Castañeda C. Breast cancer delay: a grounded model of help-seeking behavior. Soc Sci Med 2011; 72: 1096–104.))

Supporting patients to make lifestyle changes to reduce cancer risk is challenging, even in better health systems. Poor and rural populations are especially disadvantaged in Latin America, because they have less information and fewer resources available, fewer diet options, and strong cultural traditions that prevent them from adopting new behaviors. In many Latin American countries, the tobacco industry has considerable political influence, making public health initiatives involving anti-smoking policies challenging. ((Muller F, Wehbe L. Smoking and smoking cessation in Latin America: a review of the current situation and available treatments. Int J Chron Obstruct Pulmon Dis 2008; 3: 285–93)) ((Winick M. Report on nutrition education in United States medical schools. Bull NY Acad Med 1989; 65: 910–14))

Cancer screening in Latin America presents logistical challenges. With more than 100 million people lacking access to health services for geographic reasons, and 320 million people lacking health coverage, it is difficult to establish optimal cancer screening programs. ((PAHO. Latin America and the Caribbean have gained 45 years in life expectancy since 1900. http://new.paho.org/hq/index.Php?Option=com_content&view=article&id=7194&Itemid=1926 (accessed Sept 12, 2012 ))) The limited numbers of health personnel and the lack of funding in many health systems in Latin America means that preventive and detection services are not widely available. The costs of the HPV vaccine, the HPV test, the mammography equipment, and the diagnostic tests compete with many other priority resources. Preparing a sufficient number of community health personnel to educate and perform population screening is a challenge in many settings. Countries with limited health care budgets often allocate most of their resources to therapeutic care, despite studies showing that prevention is more cost-effective. ((Smith TJ, Cassel JB. Cost and non-clinical outcomes of palliative care. J Pain Symptom Manage 2009; 38: 32–44.)) Health financing programs, including health insurance, do not always provide a full support for prevention services, with greater disadvantage for poor populations. Finally, the lack of adequate epidemiological data to monitor cancer trends in Latin America limits the ability to create optimal cancer prevention and screening programs. Monitoring trends in cancer incidence is essential to improve cancer prevention and screening strategies.