Colorectal cancer is the second most common cause of cancer deaths in the United States, and it is climbing fastest among adults under 50. In that group, rectal bleeding alone raises the odds of a colorectal cancer diagnosis by 8.5 times, according to research presented at the American College of Surgeons Clinical Congress.
The 8.5 times finding was spotlighted by the college in March 2026 and cuts against a common reflex, as bowel symptoms in younger patients are too often written off as hemorrhoids or constipation. "Colorectal cancer is highly treatable when found early, and surgical advances continue to make treatment less invasive," said Marylise Boutros, vice-chair of Digestive Diseases Research at Cleveland Clinic Florida.
A systematic review of 55 studies covering more than 188,000 younger patients published in PLOS ONE found that some adults under 50 with colorectal cancer face delays of several months from symptom onset to treatment.
One in five colorectal cancer cases in the US is now diagnosed in people younger than 54, up from about one in ten three decades ago. "Anyone experiencing these symptoms should speak with their primary care physician," said Paula Denoya, a colorectal surgeon at Stony Brook Medicine.
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The seven signs to know
1. Blood in the stool. Bright red blood on toilet paper or dark, tarry stools can signal bleeding from the colon or rectum. It is often caused by hemorrhoids, but it is also the most common symptom of colorectal cancer.
2. A persistent change in bowel habits. New diarrhea, new constipation or a lasting shift in the frequency of bowel movements that runs for more than a few days is on the American Cancer Society's list of core warning signs.
3. Narrow or pencil-thin stools. A change in stool shape can point to a growth narrowing the passage. It appears on symptom lists from both UC San Diego Health and the American Cancer Society.
4. Persistent abdominal cramping or pain. New or ongoing belly pain, especially pain that worsens over time, is a documented warning sign, and easy to blame on diet, stress or irritable bowel syndrome.
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5. Unexplained weight loss. Losing weight without trying, particularly alongside digestive symptoms, is listed by both UC San Diego Health and the American Cancer Society as a possible red flag.
6. Unusual fatigue or weakness. Slow, hidden blood loss from a tumor can leave the body low on iron and cause tiredness. "Unexplained iron-deficiency anemia should always prompt careful follow-up," said Samir Gupta, a gastroenterologist at UC San Diego Health.
7. A feeling that the bowel has not fully emptied. The American Cancer Society lists a persistent urge that is not relieved by having a bowel movement as a possible sign of a tumor in the rectum or lower colon.
Any one of these on its own is far more likely to be something benign. What tips the balance is when a symptom is new, persistent or unlike your usual pattern, especially rectal bleeding.
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When to see a doctor
Screening starts at 45 for adults at average risk, but symptoms should never be filed away as too young for cancer. Colorectal cancer caught at an early, localized stage has a five-year relative survival rate of about 90 percent, according to the American Cancer Society. If any of these symptoms lasts more than two weeks, talk to your doctor.
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This article is made and published by Jesper Bengtson, who may have used AI in the preparation.