Colonoscopy screening may be advised earlier for some people.

Colorectal cancer has risen among people under 50, and U.S. guidance now recommends routine screening beginning at age 45; certain medical conditions, inherited syndromes, family histories, or persistent symptoms are reasons a clinician might advise earlier testing.

Colorectal cancer has been increasing among people younger than 50, and recent high-profile deaths have drawn attention to that trend. Global data show a substantial rise in cancers diagnosed before age 50 between 1990 and 2019, with digestive system cancers contributing prominently. In 2023, colorectal cancer became the leading cause of cancer death in people under 50, and U.S. screening guidance was adjusted to begin at age 45. The article explains circumstances in which screening might start earlier than the routine recommendation. Key points: - Early-onset increase: Cancer diagnosed in people under 50 rose notably worldwide from 1990 to 2019, and digestive cancers, including colorectal cancer, were among the largest contributors to that rise. - Guideline change: U.S. preventive guidance lowered the routine starting age for colorectal cancer screening from 50 to 45 (reported in 2023). - Higher-risk conditions: Inflammatory bowel diseases (Crohn's disease, ulcerative colitis), a prior colorectal cancer or adenomas, and inherited syndromes such as Lynch syndrome or familial adenomatous polyposis are cited as reasons to begin screening well before age 45. - Symptoms vs. screening: Persistent symptoms such as changes in bowel habits, rectal bleeding, or ongoing abdominal pain are treated as reasons for diagnostic evaluation rather than routine screening. Summary: The documented rise in early-onset colorectal cancer contributed to the change in routine screening recommendations to start at age 45. Medical conditions, certain genetic syndromes, and a family history of early colorectal cancer are factors that clinicians report as prompting earlier testing. Diagnostic testing is used when symptoms are present. Undetermined at this time.