Epidemiology of colonic adenoma and cancer.

Colorectal cancer (CRC) remains a major global health concern, showing significant variation in incidence and trends across different populations and age groups. While overall rates in older adults have declined in many high-income countries due to effective screening, the incidence of early-onset CRC, diagnosed before age 50, has been rising worldwide, especially in East Asia. Both early- and late-onset CRC share many risk factors, broadly categorized as modifiable and non-modifiable. Non-modifiable factors include age, sex, family history, hereditary syndromes, and inflammatory bowel disease. Modifiable factors such as obesity, unhealthy diet, physical inactivity, smoking, and alcohol consumption play a substantial role in CRC development and offer important targets for prevention. Lifestyle modifications-including weight control, regular physical activity, smoking cessation, and a balanced diet rich in fiber and vegetables-are associated with reduced CRC risk. In selected individuals, chemoprevention with low-dose aspirin may also lower CRC incidence. Screening and early detection remain essential strategies to reduce the CRC incidence and mortality, while comprehensive prevention efforts are needed to address the growing burden of CRC across diverse populations.