Colorectal cancer has become the deadliest cancer among Americans under 50, a troubling shift that has prompted medical organizations to sound the alarm on early warning signs that younger patients often overlook or dismiss.
The surge is dramatic. About one in five colorectal cancer diagnoses now occurs in people younger than 54, compared to one in ten cases three decades ago. The disease remains more common in older adults, with roughly one in 25 people developing it over their lifetime, but the uptick in younger patients has forced a reckoning among gastroenterologists and surgeons about how symptoms get missed.
The American College of Surgeons recently launched free educational tools and a symptom checklist specifically designed to help younger adults and their doctors recognize colorectal cancer earlier. The push comes from frustration in the medical community over misdiagnosis.
"When younger patients come in with bowel symptoms, those are too often blamed on hemorrhoids or constipation and treated conservatively without proper investigation," said Marylise Boutros, a colorectal surgeon and vice-chair of Digestive Diseases Research at Cleveland Clinic Florida, who helped develop the new materials. "Awareness of the subtle signs can save lives."
The checklist identifies several red flags that should never be ignored, especially when new or persistent.
Bowel Changes That Matter
Lasting shifts in bowel habits deserve medical attention. This includes constipation, diarrhea, unusually narrow stools, or the sensation that your bowel has not fully emptied. Some patients report rectal pressure or discomfort, which can develop when a tumor inflames tissue or partially blocks the intestine.
"These symptoms in younger patients can sometimes stem from noncancerous conditions," said Paula Denoya, a colorectal surgeon at Stony Brook University Hospital. "But any bowel change that is new or different for you warrants a medical evaluation. Bring it up at your annual wellness visit."
Blood in the stool stands out as perhaps the most critical warning sign. Research presented at the American College of Surgeons Clinical Congress 2025 found that rectal bleeding was the strongest predictor of colorectal cancer diagnosis in symptomatic patients under 50, raising the odds by 8.5 times.
"Bleeding is the most common symptom of colorectal cancer, though other diseases cause it too," explained James T. McCormick, a colorectal surgeon and professor at Drexel College of Medicine. "People may see bright red blood on toilet paper or in the bowl, or it may appear dark or tarry when mixed in stool. Any amount of recurring blood needs evaluation and possibly a colonoscopy to identify the cause."
Changes in stool appearance beyond bleeding also warrant investigation. Bright red stool, dark or tarry stools, or mucus in the stool can signal bleeding in the gastrointestinal tract or colon. While these changes do not automatically point to cancer, they should be evaluated if they persist or return.
General health shifts should not be ignored either. Unexplained weight loss, persistent fatigue, weakness, reduced appetite, nausea, or vomiting can reflect colorectal cancer or other gastrointestinal problems serious enough to discuss with a doctor.
Standard screening for average-risk adults begins at age 45, according to the U.S. Preventive Services Task Force. However, those with a family history of colorectal cancer or inflammatory bowel conditions like Crohn's disease or ulcerative colitis should begin sooner. Colonoscopy remains the gold standard because doctors can both identify cancer and remove precancerous polyps during the same procedure.
"Colorectal cancer is highly treatable when caught early, and surgical advances continue to make treatment less invasive," Boutros said. "Patients should use the checklist to start a conversation with their primary care provider about any concerning bowel changes."
Author Jessica Williams: "The fact that doctors still brush off these symptoms in younger patients as simple constipation or hemorrhoids is inexcusable given how much the disease has shifted in recent years. The checklist is overdue."
Comments