‘How I knew I had colorectal cancer’: Six survivors share their symptoms
December 18, 2025
Medically Reviewed | Last reviewed by David Richards, M.D. on December 18, 2025
Constipation, diarrhea, and abdominal pain can all be symptoms of colorectal cancer.
But they can also be signs of other conditions, including Crohn’s disease, irritable bowel syndrome and even a stomach virus.
So, how do you know when it’s time to see a doctor?
“Any time symptoms persist for longer than two weeks, they are cause for concern,” says gastroenterologist David Richards, M.D. “That’s particularly true if they’re accompanied by abdominal pain, bloody stools or unintentional weight loss.”
Here’s how six of our patients knew they had colorectal cancer, in their own words.
Blood in the stool or toilet bowl
“I experienced bloody stools, bowel changes, and abdominal pains for months,” recalls Anatole Karpovs, M.D., a Louisiana pediatrician who was diagnosed with stage III colorectal cancer at age 37. “But as a doctor with a busy practice and a hectic family life, I didn’t have time to be sick. So, I explained away my symptoms or minimized them. It was only later, when they became persistent enough that I couldn’t ignore them, that I finally sought treatment.”
Robert Harris was 76 when he was diagnosed with stage III colorectal cancer. “I started having dark stools and a little pain in my lower abdomen, so I called my family doctor,” says the retired army veteran and project manager. “She thought it might be my appendix, since the pain was on my right side, so she brought me in for a check-up. But then she did a digital exam and said there was blood in my stool.”
Diarrhea
Courtney Nash, who was 35 when she was diagnosed with stage III colorectal cancer, had been dealing with chronic diarrhea, frequent stomach aches and other digestive issues for more than 20 years due to ulcerative colitis.
“But after the birth of my second daughter, my symptoms increased dramatically,” says Courtney, a sugar cane farmer from Harlingen, Texas. “I started dropping weight, losing my hair and even passing blood occasionally.”
Constipation or problems having a bowel movement
“I was pregnant with my second child when I began having constipation,” recalls Catherine Wright, a stay-at-home mom from Florida who was 33 when she was diagnosed with stage III colorectal cancer. “Each night, I’d wake up with an urgent need to go to the bathroom. But then I’d sit on the toilet, unable to empty my bowels. It was annoying and interfered with my sleep.”
“I thought the inconsistent stools I was experiencing were from diet changes I’d made,” adds graphic designer Jaystan Davis, who was only 19 when he was diagnosed with stage IV colorectal cancer. “I was scared and very confused.”
Unexplained and unexpected weight loss
“Most people get a bit heavier over the holidays,” notes Kenneth Rolston, M.D., a retired MD Anderson infectious diseases specialist who was 66 when he was diagnosed with stage I colorectal cancer. “But I’d been losing weight steadily for about four months by early 2017. And I was not trying to. I was also experiencing fatigue.”
Kenneth finally made an appointment after his wife looked across the dinner table at him one night and said, “You are literally melting away before my eyes. What’s it going to take to get you to go to the doctor?”
Don’t wait to call your doctor if you see any of these symptoms
Colorectal cancer symptoms such as diarrhea, constipation, bloating and fatigue are common and non-specific enough that they could be caused by any number of conditions.
But if you experience one or more of the following “alarm symptoms,” consider it a red flag and contact your doctor immediately.
- Rectal bleeding
- Stools that are black and either loose and sticky or tarry
- Unusually severe fatigue (impedes your ability to perform daily activities)
- Low blood count
- Unintentional weight loss
- Iron-deficiency anemia
“Things like diarrhea and constipation are so general that they could be due to many possible causes,” notes Richards. “None of them necessarily means that you have colorectal cancer. But if a symptom is persistent, rather than a one-time issue, it should at least warrant a conversation with your doctor. And, some symptoms, such as rectal bleeding, black stools, and anemia, should prompt a visit to your doctor, if they haven’t already been evaluated.”
Request an appointment at MD Anderson online or call 1-877-632-6789.
Key takeaways
- See a doctor if symptoms like diarrhea, constipation or bloating don’t resolve on their own within a few weeks.
- Excessive fatigue and losing weight without trying may also be symptoms of colorectal cancer.
- Contact a doctor immediately if you see blood in your stool.
A persistent symptom should at least warrant a conversation with your doctor.
David Richards, M.D.
Physician