Colon cancer is a type of cancer that occurs in the large intestine or the rectum. Most colon cancers originate from small benign tumors called adenomatous polyps that form on the inner wall of the colon.
Adenomatous polyps can develop into malignant colon cancer over time if not removed or left untreated. Colon cancer cells will invade and destroy healthy tissue around the tumor and causing many complications.
Some health experts agree colon cancer and rectal cancer as a group, called colorectal cancer. Rectal cancer originates in the rectum, which is in the end of the colon, closest to the anus.
In the United States, about 112,000 people are diagnosed with colon cancer and approximately 40,000 people with rectal cancer each year.
Types of Colon Cancer
More than 95% of colon cancer and rectal cancer is adenocarcinoma. This cancer starts in the cells that coat the lining of the colon and rectum.
The other 5% of colon cancer are consists of a less common cell types including carcinoid tumor, gastrointestinal stromal (GISTs), leiomyosarcomas, lymphomas, melanomas, neuroendocrine tumors, and signet ring cell tumors.
Colon Cancer Causes and Risk Factors
There is no single cause for colon cancer. Almost all colon cancers begin as noncancerous (benign) tumors, which slowly develop into cancer.
Age is the number one risk factor for colon cancer. In fact, research indicates that most colon cancer is diagnosed in people over 50 years.
- Family history of Colon Cancer
If you have family members with colon cancer, you have higher risk of colon cancer especially if the cancer was diagnosed at a young age.
- Family history of Colon Polyps
Almost all colon cancers develop from adenomatous polyps in the colon, generally referred to simply as colon polyps. People who have personal or family history of colon polyps are at higher risk for colon cancer.
- Smoking and Alcohol consumption
Smoking cigarettes and drink alcohol are definitely linked to colon cancer risk. While smoking and drink alcohol do not directly cause colon cancer, they are weakens the body in many ways and has no health benefits.
People with diabetes have a greater chance of developing colon cancer. Generally, people with diabetes are 40 percent more likely to develop colon cancer than those who don’t have diabetes.
Obesity has been identified as a risk factor for colon cancer.
Twenty five percent of all colon cancers occur when the person has a genetic disease. Two of the most common genetic causes of colon cancer are hereditary nonpolyposis colorectal cancer (HNPCC), also known as Lynch syndrome, and familial adenomatous polyposis (FAP).
What you eat may play a role in your risk of colon cancer. Diets high in fat, low fiber and red meat have been found to cause colon cancer. However, some studies found that the risk does not drop if you switch to a high-fiber diet, so the cause of the link is not yet clear.
- Inflammatory Bowel Disease
Inflammatory bowel disease, often characterized by conditions such as ulcerative colitis and Chron’s disease, increases the risk of colorectal cancers. In general, the longer a person has inflammatory bowel disease, the greater risk of developing colorectal cancers.