Incidence Trends of Colorectal Cancer by Social and Behavioral Factors-A Pooled Cohort Study

Colorectal cancer (CRC) represents more than 10% of the global cancer burden. Unlike in some other cancers, no single risk factor accounts for most CRC cases. Despite the well-studied overall incidence trend of CRC, little information is available on risk factor-specific incidence trends of CRC. This study aims to evaluate the rarely studied incidence trends of CRC in males and females with variable levels of exposure to specific risk factors, including education level, cigarette smoking, alcohol consumption, physical inactivity, and body mass index (BMI). We used Finnish pooled cohort data from seven cohorts linked to the population-based Finnish Cancer Registry. The pooled data included 224,048 subjects, of whom 2006 were diagnosed with CRC. CRC incidence adjusted for known risk factors increased annually by 1.7% in males and 1.0% in females. In risk factor-stratified analysis, the average annual percentage increase in CRC incidence was especially high in current male smokers. This study further strengthens the evidence that living with overweight or obesity, having a tall body height, or living with diabetes mellitus (DM) associates with an increased risk of CRC. Cigarette smoking was associated with an increased CRC risk in males, while heavy alcohol consumption was associated with an increased risk in females. In this study, education level or physical inactivity were not statistically significant risk factors for CRC. Our findings highlight the need for effective public health strategies, with special emphasis on preventing overweight, obesity, and smoking along with other modifiable lifestyle factors known to affect CRC risk.