Colon Cancer Symptoms and Signs

Doctor with large intestine model
Doctor with large intestine model. Getty Images/ericsphotography/E+

Colon cancer does not always present symptoms in the early stages. Colon cancer symptoms usually do not appear until the disease has progressed into an advanced stage. This makes screening highly valuable -- it can detect colon cancer in the early stages, before symptoms begin to appear.

Blood in the Stool

Blood in the stool is a common symptom of colon cancer, but you can't always actually see blood that may be in the stool.

Tests like the fecal occult blood test (FOBT) detect blood that may be unseen to the naked eye. It is also associated with less-severe health problems, such as hemorrhoids and anal fissures.

Some foods, like beets, watermelon, and red licorice can make the stools turn red. To be on the safe side, always report suspicious stool activity to your doctor.

Thin Stools

The size of our stool gives us good insight to what may be going on in our bowel. Thin or ribbon-like stools can indicate that there may be an obstruction -- something is blocking the passage of stool, like a tumor. Other conditions may also cause thin stools, like a large benign polyp or hemorrhoids.

How thin is too thin? A thin stool is considered to be as thin as a pencil. If you consistently notice thinner stools, even if they aren't as thin as a pencil, let your doctor know.


Constipation is a non-specific symptom of colon cancer. Frequent constipation can be the symptom of many things, more than likely a condition much less serious than colon cancer. However, chronic constipation can be serious, so it is important to let your doctor know.

In reference to colon cancer, constipation occurs when a tumor is obstructing the colon.

Feeling Like You Have to Empty Your Bowel, Even When You Don't

If you feel like you have to empty your bowel, even after just doing so, or simply feel like there is something in your bowel, talk to your doctor. This can indicate the presence of a tumor, which causes the bowel to feel full, even when it is not.

Abdominal Pain

Abdominal pain is also a vague symptom. This can occur when the colon is blocked by a tumor. Gas pains are also common because tumor obstruction doesn't allow the gas to travel properly through the colon to exit the body.


Fatigue that lasts more than a few days can indicate a medical problem. In relation to colon cancer, fatigue is often related to anemia, because of blood loss in the stool. Like other symptoms of colon cancer, fatigue is a vague symptom and can be related to many other less serious conditions.

Talking to Your Doctor About Colon Health

Many people feel shy to talk about bowel habits with their doctor. This can easily lead to an avoidable delay in diagnosing colon cancer. Remember, the earlier colon cancer is diagnosed, the easier it can be treated with a better prognosis.

Continue Reading