The Colon and Rectum

The colon and rectum are parts of the digestive system. They form a long, muscular tube called the large intestine (also called the large bowel). The colon is the first 4 to 5 feet of the large intestine, and the rectum is the last several inches.

Partly digested food enters the colon from the small intestine. The colon removes water and nutrients from the food and turns the rest into waste (stool). The waste passes from the colon into the rectum and then out of the body through the anus.

Symptoms of colorectal cancer

A common symptom of colorectal cancer is a change in bowel habits. Symptoms include:

• Having diarrhea or constipation
  
• Feeling that your bowel does not empty completely
  
• Finding blood (either bright red or very dark) in your stool
  
• Finding your stools are narrower than usual
  
• Frequently having gas pains or cramps, or feeling full or bloated
  
• Losing weight with no known reason
  
• Feeling very tired all the time
  
• Having nausea or vomiting
  

Most often, these symptoms are not due to cancer. Other health problems can cause the same symptoms. Anyone with these symptoms should see a doctor to be diagnosed and treated as early as possible.

Usually, early cancer does not cause pain. It is important not to wait to feel pain before seeing a doctor.