Colorectal Cancer Overview
Colorectal cancer is cancer that affects the lower part of the Gastrointestinal tract, that is, the large bowel and rectum.
It is the 3rd most common type of cancer in humans and in about 80% of cases it occurs in people more than 55 years of age. In 2016, there will be 134,490 estimated new cases of colorectal cancer in the US, accounting for approximately 8% of all new cancer cases nationwide.
Over 90% of cases of colorectal cancer begin as small, non-cancerous bowel lesions called polyps which grow on the inner wall of the colon or rectum. Studies show that most of these polyps will become cancer with time if left undiagnosed and untreated.
Causes and risk factors
As for most types of cancer, it is unclear what causes colon cancer. However, several conditions and risk factors have been described that contribute to the pathogenesis of colon cancer, such as:
- Obesity. People who are obese have a much higher chance of developing colorectal cancer than non-obese individuals.
- Older age. The risk increases significantly after the age of 50.
- Inflammatory Bowel Disease (IBD). Chronic inflammatory disease of the colon such as Crohn’s disease and Ulcerative Colitis greatly increase the risk of colorectal cancer.
- Inherited genetic syndromes such as Familial Adenomatous Polyposis (FAP) can increase the risk for colorectal cancer.
- Low-fiber, high-fat diet. People on diets rich in fat, red and processed meat and low in fiber are at greater risk.
- Sedentary lifestyle