Colorectal cancer is one of the most common types of cancer, and the science shows that physical activity alone is a key factor in reducing the risk of adenoma. However, it should be kept in mind that an adenoma is not cancer. In other words, we’ve shown that physical activity helps prevent the disease from even occurring because it reduces the risk of developing a precursor. Sedentary behavior in adolescence has been a major concern, especially in connection with colorectal cancer. Although in most cases the disease appears after the age of 60, the number of patients under 50 is rising. Scientists still don’t know if this is because more people are being diagnosed or undergoing colonoscopies, or whether early exposure to risk factors such as a sedentary lifestyle may be driving the earlier incidence of colorectal adenoma or cancer. According to the researchers, physical activity may reduce the risk of carcinogenesis by decreasing body fat, inflammation and insulin levels. Free fatty acids and insulin may promote either gut inflammation and stumulate mucosal cell proliferation. Very recently, for example, it has been published an epidemiologic research form researchers in the Department of Preventive Medicine at the University of São Paulo’s Medical School in Brazil, about the possibility to prevent the onset of youth gut polyposis with simple lifestyle changes.
Colorectal cancer is the third most frequent type of cancer in Brazil, but the effects of more than 1 hour of moderate daily physical exercise, such as walking, accumulate throughout life and are associated with a 39% reduction in the risk of advanced adenomatous polyps. Scientists are already aware that the links between physical activity, adenomas and colorectal cancer do exist, but this is the first study to demonstrate the cumulative effects of physical activity starting in adolescence on the incidence of colorectal adenoma. The study published this year analyzed the association between physical activity during adolescence and risk of adenoma later in life and adjusted for such known risk factors as smoking, diet, alcohol intake, and family history of colorectal cancer. The authors analyzed the data of 28,250 women included in the Nurses’ Health Study II (NHS II), one of the largest investigations into risk factors for major chronic diseases ever performed. The sample population included women aged 25-42 years who were employed as nurses and medical residents in the United States. It was one of a series of prospective cohort studies conducted to examine the etiology of chronic diseases and the long-term effects of physical activity, nutrition, hormones and the environment, among other factors, on health and disease development.
Each set of two-year cohort members received a follow-up questionnaire with questions about diseases and health-related topics, including smoking, hormone use, pregnancy history, and menopausal status. The 1997 questionnaire was the first to include items relating to physical activity, diet and obesity during adolescence (when they were between 12 and 22 years of age). They answered questions on home-school commute times and methods, and on moderate physical activity such as walking as well as more intense exercise such as gym classes, swimming and other sports. This enabled us to estimate the level of physical activity during their adolescence. Follow-up continued until 2011, when the questionnaire included further items on lifestyle habits between the ages of 23 and 64, a period in which the nurses responded the questionnaire every 2 years. To participate in the study, the nurses had to have undergone at least one sigmoidoscopy or colonoscopy, since polyps and adenomas are asymptomatic. The results of the analysis showed that physical activity in adolescence (12-22) reduced the risk of adenoma by 7% compared with little or no physical activity (less than 60 min/day). Physical activity in only adulthood (23-64) reduced the risk by 9%. Physical activity in both adolescence and adulthood reduced the risk by 24%.
The finding that most surprised the researchers, however, was that adequate physical activity in both adolescence and adulthood reduced the risk of advanced adenoma by 39%. This increased level of risk reduction correlated with villous adenomas, which are aggressive polyps with a diameter of more than 1 cm and are the most likely to evolve into colorectal cancer. THis study enlarges the possibility to treat in advance the onset of gyt polyps that may evolve in colon or colorectal cancer in adulthood. Most of the studies about polyposisi have traditionally performed in the context of familiar adenomatous polyposis (FAP), a genetic precancerous syndrome. Patients screened positive for the disease must follow a precise lifestyle and undergo periodic screening for gut anomalies or masses (polyps and the like). Usually these patients are encouraged to assume aspirin (acetylsalicilate) or other specific antinflammatories, like celecoxib, to reduce the risk to develop carcinomas from gut polyps. Another drug that would seem effectiv, especially combined with these drugs, is eflornitine (DFMO), a substance that interfere with a metabolic pathway needed by cancer cells to replicate. Two randomized clinical trials published in 2016 have proven that this strategy combining DFMO and another NSAID like celecoxib or sulindac may result beneficial at least in some extent.
Diet may have a partial impact as well, since there are proofs that certain chemopreventive molecules with antinflamammtory properties may result protective against colon cancer development. For example, omega-3 fatty acids like eicosapentenoic acid (EPA), may help reduce polyps size and probability of degeneration in vivo, as tested on patients with FAP. EPA holds promise as a colorectal cancer chemoprevention agent, especially considering its natural origin and a very favourable safety profile. This is why omega-3 intake with a balanced diet may also help delay the onset of colon or colorectal cancer since youth. The suggestion is motivationally higher for adolescents or youngsters with FAP, yet normal adolescent should receive more education about a correct nutritional and physical lifestyle. It must not be forgotten, indeed, that every biological damage done in youth is dealt with in the old age. This is biology supported by science, not a random reckoning.
- Edited by Dr. Gianfrancesco Cormaci, PhD, specialist in Clinical Biochemistry.
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