Colon cancer is cancer that begins in the large bowel (colon). Depending on where the cancer starts, colon cancer is sometimes called colon (lower part of the digestive system) or rectal (last several centimeters of the colon) cancer. Therefore, it is usually referred to as colorectal cancer.

Colon cancer can start in the small intestine, too, but it is much rarer.

Colon cancer is one of the most common types of cancer.


The symptoms of colon cancer vary according to the location of the tumor in the colon. The right colon tumours can grow to large sizes before they cause any abdominal symptoms. The left colon is narrower than the right colon. Therefore, the left colon tumours usually cause partial or complete bowel obstruction.

  • Bleeding from the rectum or blood in the stool
  • Constipation, diarrhea
  • Abdominal pains and cramps
  • Bloating
  • A lump in the abdomen (more commonly on the right side)
  • Losing weight
  • Pain in your abdomen or back passage
  • Anemia
  • Tiredness and shortness of breath due to anemia


The cause of colon cancer is not exact. There are a few causes considered taken from patients’ histories:

  • polyps – therefore regular screening (colonoscopy) is necessary because some polyps can turn into cancer
  • high-fat diet
  • family history
  • inflammatory bowel disease, especially chronic ulcerative colitis
  • genetic conditions, like familial adenomatous polyposis and hereditary non-polyposis colorectal cancer
  • age
  • smoking
  • alcohol
  • obesity

Risk Factors

The risk factors for developing colon cancer are:

  • Age – more common in people over 50
  • Ethnicity – higher incidence is observed in African-American race
  • Polyps
  • Inherited syndromes
  • Ulcerative colitis
  • Family history
  • High-fat diet
  • Diabetes
  • Physical inactivity
  • Obesity
  • Smoking
  • Alcohol
  • Radiation therapy for cancer to treat previous cancers


Prevention of colon cancer may be possible with timely screening. Other preventive measures to be taken are:

  • eating healthy diet, avoiding high-fat and low fiber food
  • stop smoking
  • regular exercises
  • healthy weight
  • alcohol in moderate quantity
  • surgery in cases of inherited syndrome or ulcerative colitis