Genetics and Colorectal Cancer

Definition
Colorectal cancer is a cancer that is located at the lower end of the digestive tract near or around the colon or rectum. Most colorectal cancers begin as a polyp, a non-cancerous, pus-filled growth, located within the lining of the colon or rectum. According to the National Cancer Institute, families who’ve been affected by conditions such as juvenile polyposis, Peutz-Jeghers syndrome, hyperplastic polyposis, and colon adenomas may have an increased risk of developing colorectal cancer. 

Cause & Risk Factors
Research suggests colorectal cancer may be caused by genetic mutations within colon-cancer prone families. This condition is often inherited in an autosomal dominant way, meaning, an abnormal gene from only one parent can lead to colorectal cancer. According to the National Cancer Institute, there is also at least one case of autosomal recessive inheritance recorded to date, which is MYH-associated polyposis (MAP).

The research institute also determined that the inheritance risk of colorectal cancer is equal in both males and females (50%). Additionally, parents who carry an autosomal dominant genetic predisposition increase their child’s chance of inheriting the predisposition by 50%. The risk is equal in both male and female children. Other risk factors of colorectal cancer generally include:

  • Older age (50+ years old)
  • African American race
  • Personal history of polyps
  • Personal history of chronic inflammatory diseases of the colon
  • Diabetes
  • Smoking
  • Obesity
  • Alcohol abuse