March is Colorectal Cancer Awareness Month. Colon cancer, also known as colorectal cancer, is a form of cancer that affects the large intestine and rectum. Colon cancer is one of the leading causes of cancer-related deaths in the United States and can develop without symptoms. For this reason, it is important to stay on top of your colon health. Colon cancer develops when cells in the colon or rectum grow out of control. Colorectal cancer usually begins as a growth on the inner lining of the large intestine, but it is preventable and highly curable if detected in early stages.