Colorectal cancer, which includes colon and rectal cancers, is the fourth most common cancer in the U.S. and the second leading cause of cancer deaths. Rates in young people have nearly doubled since 1995. Many symptoms—like constipation, diarrhea, and fatigue—are easily dismissed as irritable bowel syndrome or food sensitivities. Doctors emphasize knowing the warning signs, with bowel incontinence being a particularly concerning symptom that patients should not ignore.
Bowel Incontinence as a Sign of Colorectal Cancer
Bowel leakage, or fecal incontinence, is not a common symptom but can occur, especially with rectal cancers, according to Dr. Jason B. Carter, a urologist and medical adviser with Aeroflow Urology. Dr. Ketan Thanki, a board-certified colorectal surgeon at MemorialCare Todd Cancer Institute, explains several mechanisms: rectal cancer can reduce the rectum's ability to sense stool, weaken anal sphincter nerve signals, cause mucus secretion leading to diarrhea, or create a narrowing that forces liquid stool through. Typically, this symptom appears later in the disease course, as Dr. Nikiya Asamoah, a gastroenterologist in Washington, D.C., notes: obstruction develops when a cancerous lesion becomes large enough to block formed stool. However, bowel leakage is more often caused by non-cancerous conditions such as aging, pelvic floor dysfunction, hemorrhoids, or inflammatory bowel disease.
Other Signs of Colorectal Cancer
Earlier symptoms include rectal bleeding, blood in stool, persistent changes in bowel habits, new constipation, diarrhea, narrowing of stool caliber, abdominal pain, unexplained weight loss, iron-deficiency anemia, excessive fatigue, a feeling of incomplete bowel emptying, and pencil-thin stools. Dr. Carter stresses that colorectal cancer can be present for a long time without obvious symptoms, making screening crucial. Right-sided colon cancers often cause no bowel changes, presenting only as fatigue or weight loss, according to Dr. Thanki.
Prevention and Treatment
Preventable risk factors include alcohol and tobacco use, processed foods, excessive red meat, and low dietary fiber. Regular screenings, starting at age 45, are vital. Dr. Thanki notes that early-stage colorectal cancer is usually surgically treatable, while advanced cases may require chemotherapy, radiation, or immunotherapy. “We have never had as many good treatments available as we do now,” he said.
When to See a Doctor
Dr. Thanki recommends seeing a doctor if any GI symptom persists for more than a few weeks. “The last thing you want to do is ignore a change in bowel habits for months or years,” he said. Dr. Carter adds, “Colorectal cancer is one of the most preventable cancers we face today. Early detection dramatically improves outcomes.”
