man on toilet

Is it possible for diarrhea to be the only symptom of colon cancer?

You may be familiar with colon cancer’s classic signs such as abdominal pain, weakness, weight loss, blood in stools and ribbon-like stools — and diarrhea and/or constipation.

I wondered, however, if colon cancer can cause just the symptom of diarrhea.

I posed this question to gastroenterologist Whitney Jones, MD, Clinical Professor of Medicine, University of Louisville, and Founder, Colon Cancer Prevention Project.

Dr. Jones says: “Yes, diarrhea alone can be a symptom, particularly if this is a new and persistent change in habits.

“Tumors in the lower colon or rectum cause a partial obstruction of the bowel, which compensates by liquefying the stool to get stool past any narrowed portion.”

The tricky thing about this is that diarrhea is a symptom of tons of medical conditions, most of them benign.

This symptom is so common that you can’t watch prime time TV without seeing a diarrhea commercial.

Millions of people have suffered a sudden onset or gradual onset of diarrhea without knowing the cause, at least initially.

I then asked Dr. Jones if there’s a bowel obstruction, can we assume that once the obstruction starts creating enough blockage to cause diarrhea, that there will be “no going back” to formed stools?

Or can the tumor sometimes shift position and thus result in normal stools?

He responds, “The process, like irritable bowel syndrome, can wax and wane in the short-run (i.e., 1-2 weeks), but in general does not just stop and reverse to normal. It will usually be unremitting and eventually leads to obstruction if not diagnosed sooner.”

When having even a routine colonoscopy, if you’ve been enduring diarrhea lately, make sure your physician knows about this.

This way, the endoscopist can collect tissue samples of your colon for microscopic analysis to see if an inflammatory condition is responsible for your symptoms.

For example, ongoing diarrhea for no apparent reason can be caused by microscopic colitis.

Dr. Jones explains, “The time to be screened for colon cancer is while you are asymptomatic. Otherwise, it is not a screening test; it is a diagnostic test.

“When you do have a GI problem (as we all will ), if you had been screened, you are much less likely to have the cause of your issue be colon cancer.”

dr. jonesDr. Jones practice interests include prevention and treatment of colon cancer, pancreatic disease and biliary disease. He has authored numerous scientific articles, reviews and abstracts and presented at a variety of national and international scientific meetings.