Colorectal Cancer: Symptoms and Signs

This section has been reviewed and approved by the Cancer.Net Editorial Board, 09/2013

ON THIS PAGE: You will find out more about body changes and other things that can signal a problem that may need medical care. To see other pages, use the menu on the side of your screen.

It is important to remember that the symptoms and signs of colorectal cancer listed in this section are the same as those of extremely common noncancerous conditions, such as hemorrhoids and irritable bowel syndrome. When cancer is suspected, these symptoms usually have begun recently, are severe and long lasting, and change over time. By being alert to the symptoms of colorectal cancer, it may be possible to detect the disease early, when it is most likely to be treated successfully. However, many people with colorectal cancer do not have any symptoms until the disease is advanced, so people need to be screened regularly. People with colorectal cancer may experience the following symptoms or signs. As mentioned above, it is also possible that these symptoms may be caused by a medical condition that is not cancer, especially for the general symptoms of abdominal discomfort, bloating, and irregular bowel movements.

  • A change in bowel habits
  • Diarrhea, constipation, or feeling that the bowel does not empty completely
  • Bright red or very dark blood in the stool
  • Stools that look narrower or thinner than normal
  • Discomfort in the abdomen, including frequent gas pains, bloating, fullness, and cramps
  • Weight loss with no known explanation
  • Constant tiredness or fatigue
  • Unexplained iron-deficiency anemia (low number of red blood cells)

Talk with your doctor if any of these symptoms last for several weeks or become more severe. And talk with your doctor if you are concerned about any symptom or sign on this list and ask to schedule a colonoscopy to find the cause of the problem.

Since colon cancer can occur in people younger than the recommended screening age and in older people between screenings, anyone at any age who experiences these symptoms should visit a doctor to find out if he or she should have a colonoscopy.

Your doctor will ask you questions about the symptoms you are experiencing to help find out the cause of the problem, called a diagnosis. This may include how long you’ve been experiencing the symptom(s) and how often.

If cancer is diagnosed, relieving symptoms and side effects remains an important part of cancer care and treatment. This may also be called symptom management, palliative care, or supportive care. Be sure to talk with your health care team about symptoms you experience, including any new symptoms or a change in symptoms.

The next section helps explain what tests and scans may be needed to learn more about the cause of the symptoms. Use the menu on the side of your screen to select Diagnosis, or you can select another section, to continue reading this guide.