Colorectal Cancer or GI Disorder? How to Tell

Medically Reviewed by Minesh Khatri, MD on March 08, 2022
3 min read

Colorectal cancer can seem a lot like some common gastrointestinal (GI) disorders, including hemorrhoids, irritable bowel syndrome (IBS), an infection, or inflammatory bowel diseases (IBD), such as Crohn’s disease or ulcerative colitis. They usually have many of the same symptoms.

Many of the conditions, including IBS, diverticulitis, and IBD, can cause belly pain, cramps, diarrhea, constipation, or a mix of these symptoms.

Along with those, Crohn’s and ulcerative colitis may make you lose weight without trying, and make your stool look bloody or black. You could also see blood in the toilet or on tissue if you have hemorrhoids, though it usually looks bright red.

Colorectal cancer can cause any of these symptoms, but there are a few key differences, too.

In the early stages of colorectal cancer, most people won’t have any symptoms. They usually show up later on, after the disease has grown and spread inside the body. The key is that they are persistent and stick around for more than a few days.

The warning signs to watch for are:

  • Blood in your poop or on toilet tissue
  • Diarrhea, constipation, or poop that’s narrower than usual
  • Feeling like you can’t finish a bowel movement, even right after you have one
  • Belly pain or cramping
  • Feeling weak and tired
  • Losing weight without trying

Most colorectal cancer starts out as a polyp, or small growth, in the intestine. Not all polyps become cancer, but some do. If your doctor can find and remove them, it’s possible to prevent colorectal cancer. In fact, the earlier you get treatment, the easier the cancer is to cure.

Experts recommend that most people get screened for colorectal cancer regularly once they turn 50. People who have a family history of the disease, though, may need to get screened earlier.

Certain GI disorders, like inflammatory bowel disease, also raise the odds of colorectal cancer. And it can be hard to tell their symptoms apart. So if you have Crohn’s disease or ulcerative colitis, especially if you’ve had them for a long time, you may benefit from earlier, more regular screening. Make sure to let your doctor know if you have any new symptoms that worry you.

If you’re having symptoms, it’s best to make an appointment with your doctor to figure out if they could be caused by a GI disorder, colorectal cancer, or another problem. Trust your instincts, whether you have a specific problem or something less concrete, like feeling you can’t quite finish bowel movements once you start them.

Your primary care doctor may decide to refer you to a specialist called a gastroenterologist. These doctors have extra training in diagnosing GI disorders and colorectal cancer.

Some of the screening tests the doctor might use include:

  • A colonoscopy: This test uses a flexible tube with a camera on the end to look inside your colon and rectum. During the exam, the doctor can remove any suspicious polyps. They can also take samples of tissue to test in a lab for signs of cancer.
  • Stool tests look for tiny amounts of blood in your poop. Another type checks it for specific DNA markers that could be a sign of colorectal cancer.
  • Flexible sigmoidoscopy: This test uses a flexible tube with a camera to let your doctor look inside the lower part of your colon and your rectum. Doctors often do a stool test along with it to look for blood.
  • Imaging tests, such as X-rays, computed tomography (CT) scans, and magnetic resonance imaging (MRI). These tests can make images of the whole colon by using X-rays and computers. One type, called a CT colonography or virtual colonoscopy, makes pictures of the entire colon and rectum to look for polyps or cancer. If the doctor sees a problem area, they’ll need to give you a regular colonoscopy to take a closer look and get a sample of tissue for testing.

Your doctor can help you choose the best test.