Colorectal cancer is one of the most common cancers worldwide and a major cause of cancer death, yet it is also highly preventable and often curable when detected early. It usually develops slowly from benign growths in the lining of the colon or rectum called polyps. Over many years, some polyps can accumulate genetic and epigenetic changes that transform them into malignant tumors.

Age is a key risk factor, with most cases occurring after 50, but incidence in younger adults is rising. Lifestyle factors such as diets high in red and processed meat, low fiber intake, obesity, physical inactivity, smoking and heavy alcohol use increase risk. A family history of colorectal cancer or certain inherited syndromes, as well as chronic inflammatory bowel diseases, also raises risk.

Screening is central to prevention and early detection. Colonoscopy allows direct visualization and removal of precancerous polyps. Other tools include stool tests that detect hidden blood or tumor DNA, sigmoidoscopy, CT colonography and emerging blood based assays. Screening strategies are tailored to age, risk profile and local resources.

Treatment depends on stage and can involve surgery, chemotherapy, radiotherapy, targeted therapies and immunotherapy. Early stage disease is often curable with surgery alone, while advanced cancers may be controlled for years with combined approaches guided by molecular profiling of the tumor.

Research is focusing on understanding tumor biology, improving noninvasive screening, refining personalized therapy and addressing disparities in incidence and outcomes. Public health efforts emphasize lifestyle modification, awareness of symptoms such as rectal bleeding and changes in bowel habits, and adherence to recommended screening.