Colorectal cancer: what to know about symptoms and screening

Colorectal cancer often begins as a polyp and is the fourth most common cancer in the U.S.; major medical groups now recommend regular screening begin at age 45.

Colorectal cancer is the focus during Colorectal Cancer Awareness Month, and experts in the article outline how the disease develops, who is affected, and how it is detected and treated. The piece explains that tumors typically begin as benign polyps in the colon or rectum and that colon and rectal cancers are treated differently. It reports recent guideline updates that recommend starting regular screening at age 45 and continuing through age 75. The article also summarizes available screening options and common symptoms when they occur. Key facts: - Colorectal cancer starts in the colon or rectum and most tumors are adenocarcinomas. - The CDC describes it as the fourth most common cancer in men and women and the fourth leading cause of cancer deaths in the U.S. - The American Cancer Society estimates more than 158,000 new colorectal cancer cases and about 55,230 deaths this year. - Rates have declined since the mid-1980s in older adults, but incidence rose about 2.9% per year among people under 50 from 2013 to 2022. - Screening options include stool-based tests, blood-based tests, and visual exams such as colonoscopy; colonoscopy is more sensitive while other tests can increase access. - Many early-stage cancers and premalignant polyps cause no symptoms; when symptoms occur they can include rectal bleeding, changes in stool color or shape, altered bowel habits, unexplained weight loss, or anemia. Summary: Updated guidance from major medical organizations recommends regular screening for most adults beginning at age 45 and continuing through age 75, with individualized decisions advised for those aged 76 to 85. Because many early cases are asymptomatic and outcomes depend on stage at detection, the availability of multiple screening methods may affect how and when cancers are identified and treated.