Colorectal cancer warning signs are increasingly relevant for people under 50, as the disease has become the leading cause of cancer related death in that age group. Although routine screening typically starts at 45 for those at average risk, symptoms can emerge earlier and should be reviewed with a health care professional at any age.
To encourage earlier recognition and prompt conversations with clinicians, the American College of Surgeons has released free public education materials and a pre-visit checklist designed to help patients prepare for primary care appointments.
Colorectal cancer warning signs and a rising trend
Marylise Boutros, MD, FACS, FRCSC, FASCRS, a member of the ACS Patient Education Committee and a colorectal surgeon who serves as vice-chair of Digestive Diseases Research at the Cleveland Clinic Florida, said bowel symptoms in younger adults are often attributed to hemorrhoids or constipation and managed conservatively. She said greater awareness of subtle indicators can save lives and that the ACS tools are intended to keep discussions focused on colorectal cancer concerns.
While the disease still occurs more often in older adults, approximately 1 in 25 men and women will develop colorectal cancer over a lifetime. Diagnoses in younger adults continue to climb. According to the American Cancer Society, about 1 in 5 cases now occur in people younger than 54, up from 11% three decades ago.
Colorectal cancer warning signs that merit evaluation
Early indicators can be mild or resemble common gastrointestinal issues. New, persistent, or unusual symptoms should be assessed by a medical professional.
The ACS checklist highlights several areas of concern.
Persistent changes in bowel habits
Constipation, diarrhea, unusually narrow stools, or sustained changes in normal bowel patterns may point to an underlying issue. Some individuals may feel incomplete evacuation or experience rectal pressure or discomfort, which can arise when a tumor causes inflammation or partial blockage.
Paula Denoya, MD, FACS, FASCRS, Commission on Cancer State Chair of the Eastern Long Island-New York chapter and a colorectal surgeon at Stony Brook University Hospital, noted that benign conditions can cause similar symptoms in younger patients. She advised that any new or different bowel change warrants medical attention and can be raised during annual wellness visits.
Recurring blood in the stool
Repeated rectal bleeding is a significant warning sign. Research presented at the ACS Clinical Congress 2025 reviewed symptomatic patients under 50 who underwent colonoscopy and found rectal bleeding to be the strongest predictor of a colorectal cancer diagnosis, increasing the odds by 8.5 times.
James T. McCormick, DO, FACS, FASCRS, CoC State Chair of the Southwestern Pennsylvania chapter, professor of surgery at Drexel College of Medicine, and chair of the Colorectal Cancer Program at Allegheny Health Network, said bleeding is the most common symptom of colorectal cancer, though other conditions can cause it. He said people may notice bright red blood on toilet paper or in the bowl, or a red or dark color mixed with stool. Any recurring blood should be evaluated, and colonoscopy may be indicated to determine the cause.
Changes in stool color or appearance
Bright red stool, dark or tarry stool, or mucus in the stool can signal bleeding somewhere in the gastrointestinal tract, colon, or rectum. These changes do not always indicate cancer, but persistent or repeated occurrences should be checked.
Unexplained changes in overall health
Colorectal cancer and other gastrointestinal disorders can produce systemic symptoms. Unexplained weight loss, ongoing fatigue, weakness, decreased appetite, nausea, or vomiting may signal an underlying problem and should prompt a discussion with a clinician.
Family history, screening, and early action
The U.S. Preventive Services Task Force advises average risk adults to begin screening at age 45. People with a family history of colorectal cancer or with inflammatory bowel diseases such as Crohn’s disease or ulcerative colitis may need to start earlier.
Several screening methods are available. Colonoscopy remains the gold standard because it can identify cancer and allow removal of precancerous polyps during the same procedure.
Dr. Boutros emphasized that colorectal cancer is highly treatable when detected early and that surgical advances are making care less invasive. She encouraged patients to use the checklist to initiate conversations with their primary care providers about any concerning bowel changes.
