Colorectal cancer usually start in the cells that line the inside of the colon and rectum. There are some other, more rare, types of tumors of the colon and rectum. It is more common in people over 50, and the risk increases with age.

Risk factors include polyps (a growth of tissue in the lining that grows into the center of the colon or rectum), a diet that is high in fat, a family history of colorectal cancer, or a history of ulcerative colitis or Crohn’s disease.

Colon and rectal cancers begin in the digestive system, also called the GI (gastrointestinal) system. The digestive system first processes food for energy, then absorbs fluid to form solid waste (stool) and finally passes from the body.

Colon and rectal cancers have much in common. Most start as a polyp (a growth of tissue in the lining that grows into the center of the colon or rectum) and develop slowly over many years. Removing a polyp early may keep it from becoming cancer. In the last 20 years, the rate of survival from colorectal cancer has been increasing in both men and women.

Colorectal cancer is considered hereditary or inherited when several generations of a family have colorectal cancer. The two most common inherited colorectal cancer syndromes are hereditary nonpolyposis colorectal cancer (HNPCC) and familial adenomatous polyposi (FAP). The children of people who carry these genes have a 50% chance of inheriting the disease-causing gene.

HNPCC is the most common form of hereditary colon cancer and accounts for about 3% of all colorectal cancer diagnoses each year. People with HNPCC often have at least three family members and two generations with colorectal cancer, and cancer develops before age 50.

FAP is a rare condition characterized by the presence of more than hundreds or even thousands of benign polyps, or growths in the large intestine and upper respiratory tract. It is thought to be present in about 1% of all people diagnosed with colorectal cancer each year. The polyps occur early in life, with 95% of people with FAP developing polyps by age 35, and are often detected in patients in their teens, with 50% developing polyps by age 15. If the colon is not surgically removed, there is almost a 100% chance that some of the polyps will develop into cancer, usually by age 40.

Signs & Symptoms

These are the symptoms most often associated with colorectal cancer, although they may be associated with other conditions:

  • A change in bowel habits
  • Blood – either bright red or very dark – in the stool
  • Diarrhea, constipation, or feeling that the bowel does not empty all the way
  • Stools that are narrower than usual
  • Frequent gas pains, bloating, fullness or cramps
  • Urge to have a bowel movement when there is no need
  • Abdominal pain or a cramping pain in your lower stomach
  • Weight loss for no known reason
  • Feeling very tired
  • Vomiting

If you notice one or more of these signs for more than two weeks, you should contact your doctor.


Treatment often depends on the location of the tumor in the colon or rectum and the stage of the disease. Your OHC doctor will help you determine the best care plan for you.

For colon cancer:

  • Surgery (techniques include colonoscopy, laparoscopy, or open surgery) is used to remove the cancer in or near the colon or rectum. Radiation therapy is more commonly used to treat pain and symptoms. A colostomy (removal of the colon) is rarely required.
  • Chemotherapy and biological therapy are used to introduce drugs into the bloodstream so they can destroy or control the cancer.

For rectal cancer:

Surgery is the most common form of treatment. Some patients receive surgery, radiation therapy and chemotherapy. While some with more advanced cases will also get biological therapy.