Colon cancer is cancer that occurs in the large intestine. Sometimes the term colorectal cancer is used to describe cancer of the colon or rectum.
Understanding colon cancer
Colorectal cancer is cancer that occurs in the lower end of the digestive tract. Colon cancer affects both males and females and is usually seen in adults over the age of 50, although studies show colorectal cancer is on the rise in younger adults.
Most colon cancer starts as a non-cancerous polyp in the lining of the intestinal wall. Colon cancer is typically slow growing, but if not removed, over time, these benign growths develop into cancer.
Screening tests are the best way to identify colon polyps and non-symptomatic colorectal cancer.
Signs & symptoms of colon cancer
There are typically no symptoms associated with colon cancer during the early stages. When symptoms do appear they are often nonspecific and include:
- Changes in bowel habits which may present as chronic constipation or persistent diarrhea
- Narrow, pencil-like stools
- Red or dark blood in the stool
- Abdominal bloating
- Weight loss that is unexplained
- Abdominal pain
- Weakness or fatigue
Causes and increased risk of colon cancer
It is not clear what causes normal cells in the colon to undergo changes in their DNA that lead to colon cancer. Certain inherited genetic conditions have been linked to the development of colon cancer including familial polyposis and Lynch syndrome.
The following are risk factors that can increase the risk of developing colorectal cancer:
- Personal history of colon cancer or adenomatous polyps – individuals who have been diagnosed with colorectal cancer or polyps in the past are at a increased risk of developing colon cancer
- Highly processed diet –researchers believe there may be a connection between colon cancer and a high fat, low fiber diet
- Inflammatory bowel diseases –those with a history of ulcerative colitis or other inflammatory bowel conditions are more likely to develop colon cancer
- Family history – those with a family history of polyps, colon cancer or inflammatory bowel disease may be considered higher risk for colorectal cancer
- Lifestyle factors – smoking, excessive alcohol consumption, being overweight or obese and a sedentary lifestyle have all been linked to a greater risk of developing colon cancer
- Race – African Americans are diagnosed at an earlier age and are more likely to die from colorectal cancer than any other ethnic group
- Age – adults over age 50 are the most at risk group for colon cancer
Diagnosing Colon Cancer
Screening tests are the best way to diagnose colorectal cancer in the earliest stages when it the most treatable. Current guidelines call for screening to begin at age 50 for most individuals, but those considered high risk should talk with their doctor about earlier screening.
Screening options for detecting cancer and/or polyps include:
- Colonoscopy – every 10 years
- Flexible sigmoidoscopy – every 5 years
- Double contrast barium enema – every 5 years
- Virtual colonoscopy (CT colonography) – every 5 years
The following screening tests detect cancer only – not polyps:
- Guiac-based fecal occult blood tests – yearly
- Fecal immunochemical tests – yearly
- DNA tests of stool – every 3 years
All abnormal screening tests should be followed-up with colonoscopy.
Treatment of Colon Cancer
Colon cancer treatment is determined by the extent of the disease.If the cancer is localized in a polyp, removal of the cancerous polyp during colonoscopy may be sufficient.
Some polyps may be removed through endoscopy, a procedure performed through a tube passed via the mouth or anus.
More extensive colon cancer requires colectomy, surgical removal of the cancer and part, or all, of the colon. In these cases, the remaining portion of the colon is reconnected to the rectum or a colostomy is performed. This procedure connects the colon to a stoma, an opening in the abdominal wall that allows waste to be collected into a bag.
Chemotherapy and/or radiation therapy may also be part of the colon cancer treatment protocol.