How does colorectal cancer develop?

All of the body's cells normally grow, divide, and then die in order to keep the body healthy and functioning properly. Sometimes this process gets out of control. Cells keep growing and dividing even when they are supposed to die. When the cells lining the colon and rectum multiply uncontrolled, colorectal cancer may ultimately develop.

Fortunately, most colorectal cancers begin as small precancerous (adenomatous) polyps. These polyps usually grow slowly and do not cause symptoms until they become large or cancerous. Colorectal cancer can be prevented by removing these precancerous polyps. Also, if detected early, colorectal cancer is potentially curable. That is why it is important to screen for colorectal polyps and cancer before symptoms develop.

What are the signs of colorectal cancer?

Even if you do not have a family history of colorectal cancer or polyps, tell your doctor if you have any of the signs that could indicate a colorectal cancer, no matter what your age. Common signs of colorectal cancer include the following:

  • Change in bowel habits (constipation or diarrhea)
  • Rectal bleeding, especially blood on or in the stool that is either bright red or very dark
  • Unusual abdominal or gas pains
  • Very narrow stool
  • A feeling that the bowel has not emptied completely after passing stool
  • Unexplained weight loss
  • Fatigue
  • Vomiting