Colorectal cancer is a term used for a type of cancer that forms in the colon or rectum—parts of the gastrointestinal system that are often grouped together because they share common features.
The vast majority of colorectal cancers are adenocarcinomas, a type of cancer that forms in the mucus-producing glands inside the colon or rectum. Less common tumors that can form in the colon or rectum are gastrointestinal stromal tumors and lymphomas.
The National Cancer Institute estimates there will be more than 142,500 new cases of colorectal cancer and more than 51,300 colorectal cancer-related deaths by the end of 2010.
As colorectal cancer develops, it could include these symptoms:
- rectal bleeding, blood in stool
- abdominal pain
- frequent gas cramps
- unexplained weight loss
- a feeling that your bowel doesn't completely empty
- changes in bowel habits, such as diarrhea or constipation
Most cases of colorectal cancer take several years to develop and begin as benign (noncancerous) clumps of cells in the colon known as polyps. While polyps are small and show few symptoms, they can eventually become cancerous. It is mainly for this reason that doctors recommend regular screenings to recognize and remove polyps before they become cancerous.
Besides polyps, other factors that can increase your risk for developing colorectal cancer include:
- family history
- being over the age of 50
- being African-American
- inflammatory intestinal conditions
- a diet low in fiber and high in fat
- radiation for treatment of other cancers