Fração prevenível da atividade física e câncer: revisão sistemática da literatura

Abstract

PREVENABLE FRACTION OF PHYSICAL ACTIVITY AND CANCER: SYSTEMATIC REVIEW OF LITERATURE. Introduction: The incidence of cancer, as well as other chronic diseases, has increased in recent years as a consequence of the modern lifestyle characterized by deregulated diet, sedentary lifestyle and exposure to chemical, physical and biological agents. Theoretical basis: Physical activity, in the last decades, is no longer part of the routine of man. It is known that the practice is related to the strengthening of the immune response, which is of extreme importance for the fight against neoplastic cells. Thus, sedentarism contributes to individuals gaining weight (a risk factor for some cancers), deregulating hormones (a risk factor for hormone-dependent cancers) and reducing the host's immune response. Objectives: To analyze the role of physical activity in cancer prevention through estimates of the preventable fraction. Methods: A systematic review of the literature according to PRISMA criteria. The descriptors employed were "physical activity", "cancer" and "risk". The search was carried out in PubMed, Scielo, bibliographical references and 20 articles of case-control and cohort studies published in English, Portuguese or Spanish were selected, which analyzed the risk modification of the most common types of cancer caused by physical activity . Results and discussion: Of the 20 articles analyzed, 50% were treated for breast cancer and the others for other cancers (cancer in general, glioma, lung, renal, colorectal, head and neck, colon, prostate, hepatobiliary and melanoma). 16 articles found negative association between physical activity and breast cancer, even after adjusting the confounding variables. In addition, in calculating the preventable fraction of each article, from the risk values, a 24.5% preventable fraction was found, corroborating the thesis that physical activity constitutes a primary prevention strategy for the cancer. The protective function of physical exercise was more prevalent in moderate to vigorous intensity exercises, domestic or leisure / sports, and for 5 to 7 days-hours / week, which is consistent with the recommendations of other literatures. However, further studies are needed to standardize the measurement of the level of physical activity and to reliably control confounding factors. Conclusion: The data collected in this study suggest that physical activity "probably" prevents the onset of cancer, mainly breast (predominantly in ER negative), lung, glioma, kidneys, head and neck, hepatic and melanoma cancer. However, it found no significant protective effect in cancer of prostate and bile ducts. For colorectal cancer the results diverged.