Lifestyle risk factors account for 27% of all cancer cases in Brazil


According to a new epidemiological study, lifestyle-related risk factors such as smoking, alcohol consumption, overweight and obesity, unhealthy diet and lack of physical activity are associated with one third of all deaths caused by 20 types of cancer in Brazil.

Published in the diary Epidemiology of cancer, the study shows that lifestyle risk factors represent 114,497 annual cases of cancer in Brazil, representing 27% of all cancer cases and 63,000 deaths, or 34% cancer mortality.

The study was conducted by researchers from the Department of Preventive Medicine of the University of Health of the University of Sao Paulo (FM-USP) and the Harvard School of Public Health in the United States, with the support of the Research Foundation of San Paolo – FAPESP.

The researchers concluded that the number of cases of laryngeal, pulmonary, oropharyngeal, esophageal and colorectal cancer could be at least halved by eliminating these lifestyle risk factors (smoking, alcohol consumption, overweight, unhealthy diet and physical inactivity) .

The most surprising finding is the proportion of cases that could be avoided by fighting lifestyle risk factors. According to several previous studies in this area, no other measure could prevent so many cases. The study should serve as a basis for the formulation of public policies to prevent cancer in Brazil ".

Leandro Rezende, researcher at FM-USP and co-author of the study

Cancer is a multifactorial disease and one of the leading causes of death in Brazil. The World Health Organization (WHO) predicts that the number of cancer cases in Brazil will increase by 50% by 2025, mainly due to population growth and population aging.

According to the new study, however, in addition to changes in population structure, the increasing prevalence of lifestyle risk factors may pose additional challenges to controlling the rate of cancer in Brazil.

"Primary prevention of cancer through lifestyle changes is one of the most attractive and realistic approaches to cancer control in Brazil," Rezende said.

According to José Eluf Neto, full professor at FM-USP and principal investigator for the study, access to parks and other leisure facilities should be part of public health policy.

"Encourage people to engage in physical activity and eat healthily and offer leisure facilities in all areas of the city so that they are close to where people live, they are primary preventive measures that should not being neglected by public administrators. A healthier lifestyle will reduce not only the number of deaths from cancer but also the number of cases of the disease, "said Eluf Neto.

There is a consensus in the scientific literature that the five lifestyle factors in question are associated with an increased risk of 20 types of cancer. The researchers calculated a metric for cancer prevention, known as the potential impact fraction (PIF); this metric is based on the population-attributable fraction (PAF) and estimates the proportional reduction in cancer cases and deaths that would occur if the exposure to the five lifestyle factors were reduced to a level corresponding to a scenario of ideal exposure.

The diet was divided into fruit, vegetables, fiber, calcium, red meat and processed meat. The researchers used data from the 2013 national IBGE health survey (Pesquisa Nacional de Saúde, PNS) to estimate the prevalence of alcohol consumption, fruit and vegetable consumption, physical activity and smoking (active and passive). ) and body mass index (BMI). IBGE is the national statistical office and the census office of Brazil.

The researchers also used the IBGE survey for the 2008-09 family budget (Pesquisa de Orçamentos Familiares, POF) to obtain data on food consumption of fiber, calcium and red and processed meat. Scientists have estimated the distribution of lifestyle risk factors by gender and age group.

The researchers considered two exposure scenarios: one with a minimal theoretical exposure to risk, assuming that lifestyle risk factors were eliminated in the entire population and the other with that which defined a plausible reduction in exposure based on political objectives and recommendations on cancer prevention.

This plausible scenario would include a 10% reduction in alcohol consumption to less than 50 g per day, an average BMI reduction of 1 kg per square meter at the population level, a calcium consumption of food of at least 200-399 mg per day and a 30% reduction in tobacco use.

Reducing unhealthy habits rather than eliminating them completely is more plausible with regard to public health policy. A significant number of cases and deaths from cancer can be avoided only by encouraging healthier habits in accordance with the recommendations on cancer prevention. "

leandror Rezende

As part of the plausible scenario for lifestyle risk reduction, 4.5% of all cancer cases (19,731 cases) and 6.1% of illness deaths (11,480 deaths) could have been avoided.

Men and women

The researchers performed several statistical analyzes to classify the correlations between the five lifestyle risk factors and the cancer in Brazil. Smoking was responsible for 67,000 cancer cases and 40,000 cancer deaths per year, representing the majority of preventable deaths, followed by a high body mass index (21,000 cases and 13,000 deaths) – closely linked to an unhealthy diet and lack of exercise – and alcohol consumption (16,000 cases and 9,000 deaths).

"We have made significant progress over the past decade in terms of laws and actions that have reduced smoking prevalence by more than half, but it remains the leading cause of cancer," said Rezende. "This reinforces the need for campaigns, taxes or surcharges and marketing restrictions. We also need to address new issues, such as electronic cigarettes, whose impact on health is unknown. We know they are a gateway to nicotine addiction, in especially for teenagers and young adults. "

A breakdown by gender showed that smoking affected men (20.8%) more than the sum of overweight, lack of physical activity, alcohol and unhealthy diet (14.2%), while for women, the sum of these four factors represented a higher percentage of preventable cases (15.2%) compared to smoking alone (10.1%).

"Our analysis of the distribution of these five factors shows that smoking is by far the main risk of cancer," Rezende said. "The difference between men and women can be explained mainly by the increased prevalence of smoking among men in Brazil, but women are also more influenced by other factors: they get less exercise and tend to be more overweight than men".


Fundação de Amparo à Pesquisa do Estado de São Paulo

Reference to the magazine:

Rezende, L. et al. (2019) Proportion of cancer cases and deaths attributable to lifestyle risk factors in Brazil. Epidemiology of cancer.

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