Overview
- Rates in adults under 50 have climbed for decades at roughly 2% a year, and recent JAMA research reports it is now the leading cause of cancer death in that age group in the United States.
- Clinicians urge younger adults not to dismiss red flags such as persistent bowel changes, blood in the stool, abdominal pain, unexplained weight loss, or iron‑deficiency anemia.
- The United States lowered routine screening to age 45 in 2021, with colonoscopy regarded as the gold standard that can detect early cancers and remove precancerous polyps.
- Researchers have not identified a single cause, with suspected contributors including processed diets, obesity, sedentary behavior, antibiotic exposure, environmental factors, and shifts in the gut microbiome.
- Studies show a heavier burden on Black Americans, which experts attribute largely to reduced access to preventive care, delayed diagnosis, and socioeconomic barriers rather than a unique genetic driver.