103 REVIEW Lib Oncol. 2020;48(2-3):103–108 doi: 10.20471/LO.2020.48.02-03.17 THE IMPORTANCE OF PHYSICAL ACTIVITY IN COLORECTAL CANCER PREVENTION NATAŠA ANTOLJAK School of Medicine, University of Zagreb and Croatian Institute of Public Health, School of Public Health Andrija Štampar, Zagreb, Croatia Summary Colorectal cancer is the second most common malignant neoplasm and the second cause of death from malignancies in both sexes. In 2017, 3689 people were diagnosed in the Republic of Croatia. Two thousand ninety-fve people died of colorectal cancer in 2019. Colorectal cancer is preventable, and it appears that smoking and obesity are factors that afect its onset. Physical inactivity is closely related to obesity, and the question is whether it can be an independent predictor of colon cancer. We searched the literature on Pubmed for the past fve years, including systematic reviews and meta-analyses on the association between physical activity and colon cancer incidence. Studies are methodologically diverse and involve difer- ent approaches. In most observational studies, greater physical activity is associated with a lower incidence of colon cancer, while in the interventional studies, results were more diverse. In general, smoking tobacco products has a much greater ef- fect on colon cancer development, but physical activity is linked to the onset of the disease and should be one of the preven- tion measures. KEYWORDS: colorectal cancer, physical activity, causal inference Corresponding author: Nataša Antoljak, School of Medicine, University of Zagreb and Croatian Institute of Public Health, School of Public Health ‘Andrija Štampar’, Rockefellerova 4, 10000 Zagreb, Croatia. e-mail: natasa.antoljak@hzjz.hr INTRODUCTION Colorectal cancer (abbrev. CRC) is the second most common cause of malignancy in both sexes (1). In the Republic of Croatia, this disease afects about 3500 people of both sexes a year were about 2100 die, a stable trend in recent years. In 2017, we diagnosed 3659 persons with CRC. In 2019, 2095 people died from this disease (3.8% of all deaths), which is the sixth leading cause of death in Croa- tia (2). Most patients do not have an inherited pre- disposition to cancer, and according to the latest data, young people born after the year 2000 have a higher risk of developing the disease (3,4,5) obe- sity increases the risk of CRC by 19%, while regu- lar physical activity reduces this risk by 24%. The risk of CRC resulting from red meat intake is af- fected by overall intake and frequency (6). Con- suming fsh can reduce the risk of CRC by 12%, while garlic intake is not signifcantly associated with a reduced risk of CRC (5). The intake of more than 20 g/day fber is associated with a 25% lower risk of CRC, and 525 mL/day of milk reduces the risk by 26% in men. Moderate amounts of alcohol (25-30 g/day) increase the risk of CRC (5). As this type of cancer is mostly preventable, it is interest- ing to ask whether physical inactivity is an inde- pendent risk factor for developing CRC. It is nec- essary to prove an independent cause-and-efect relationship between an exposure factor and the occurrence of the disease (7). In this case, it is cru- cial to prove the independent connection between physical inactivity and CRC occurrence, i.e., to prove that it is not only a factor of indirect connec- tion (confounding) on the actual causal path be- brought to you by CORE View metadata, citation and similar papers at core.ac.uk