GI malignancies can cover a variety of diseases occurring within the gastrointestinal tract from esophagus to anus. The most common malignancy is adenocarcinoma of the colon or rectum. These usually arise from polyps or small outgrowths that can grow in size to become malignant. Polyps can be identified using colonoscopy before they are malignant and can be removed to prevent the malignancy developing. The next most common malignancy that can occur in the GI tract is squamous cell carcinoma that arises in the nasopharynx, esophagus and anus. It is important to see your doctor when you have unexplained rectal bleeding, vomiting or weight loss with change in bowel habits to be evaluated for the possibility of a GI malignancy. This is usually done by referral to a gastroenterologist.