Anal cancers can occur above or below the anal verge, which marks the place where the anus changes from being inside the body to being outside the body. Cancers occurring in the anal canal (the area between the anal verge and the rectum) may be treated differently than cancers occuring in the anal margin (the area between the anal verge and the outside skin at the anus).
Colon/Rectal (Colorectal) Cancer
Most colorectal cancers start as a growth (called a polyp) on the inner lining of the colon or rectum. Not all polyps are cancerous, but some can become cancerous over time and can grow into the wall of the colon or rectum. Finding and removing precancerous polyps can prevent colorectal cancer.
The esophagus is a 10-inch long, hollow, muscular tube that connects the throat to the stomach. Esophageal cancer starts in the inner layer of the esophagus and grows outward.
Pancreatic & Biliary systems Cancer
The pancreas is an organ that sits behind the stomach. Pancreatic cancer can start in one of two types of cells in the pancreas: (1) exocrine cells, which make enzymes that help the body digest food; and (2) endocrine (also called neuroendocrine) cells, which make hormones, most importantly insulin.
The biliary system refers to the liver, gall bladder, and bile ducts.
- The liver lies under the right ribs just beneath the right lung. This page describes cancer that develops in the liver (called primary liver cancer), as opposed to cancer that has spread (metastasized) to the liver from elsewhere.
- The gallbladder is located under the liver and stores bile, a fluid made in the liver. Gallbladder cancer is rare.
- The bile ducts are thin tubes that transport bile from the liver and gallbladder into the small intestine, for help in digesting fats in food. Bile duct cancer is also called cholangiosarcoma.
Stomach (also called gastric) cancers tend to develop slowly over many years. Pre-cancerous changes often occur in the inner lining (mucosa) of the stomach and rarely cause symptoms. Cancers starting in different sections of the stomach may cause different symptoms and tend to have different outcomes.