What is Gastrointestinal Cancer?

Gastrointestinal (GI) cancer is a term used for the group of cancers that affect the gastrointestinal tract and other organs within the digestive system, including the rectum, colon, stomach, small intestine, pancreas, esophagus, liver, anus, and biliary system.

Colon and rectal cancer (colorectal):

Colorectal cancer starts in the colon or the rectum. These two cancers, often grouped together, share many similar features. Colorectal cancer often begins as a noncancerous growth called a polyp inside the colon or rectum. Since polyps don’t usually produce symptoms, regular colorectal screening is recommended for prevention.

Stomach cancer:

Stomach cancer, also called gastric cancer, is a disease in which malignant (cancer) cells form in the stomach’s lining. While stomach cancer can develop anywhere in the organ, most stomach cancers develop in the mucus-producing cells of the stomach’s inner lining, working its way through the other layers as it grows. These cancers are called adenocarcinomas.

Small intestine cancer:

Small intestine, also called small bowel cancer, occurs in the small intestine— a long tube that carries digested food between the stomach and the large intestine (colon). Small intestine cancer often begins with non-cancerous polyps, which over time, can change into cancer. Because the small intestine contains many different types of cells, different types of cancer can start there.

There are five types of small intestine cancers:

  1. Adenocarcinoma
  2. Sarcoma
  3. Carcinoid tumors
  4. Gastrointestinal stromal tumor (GIST) 
  5. Lymphoma

Pancreatic cancer:

Cancer that begins in the tissues of the pancreas— an organ that sits behind the stomach. Your pancreas releases enzymes that help digest foods (especially fats) and hormones that help control blood sugar levels.


  1. Exocrine cells
  2. Neuroendocrine cells, such as islet cells.

Esophageal cancer:

When cancer occurs in the esophagus, a hollow, muscular tube that connects the throat to the stomach, it is called esophageal cancer. It is located behind the trachea (windpipe) and in front of the spine. The esophagus helps move the food you swallow from the back of the throat to the stomach for digestion. The two most common types of esophageal cancer are:

  1. Adenocarcinoma
  2. Squamous cell carcinoma

These two esophageal cancer types tend to develop in different parts of the esophagus and develop due to different genetic changes.

Liver cancer:

Cancer that begins in the cells of the liver is called liver cancer. The liver, which is the largest internal organ, lies in the upper right portion of your abdomen, beneath your diaphragm, and above your stomach. While other cancers can affect the liver, only cancers that start in the liver are considered liver cancer (called primary liver cancer).

Secondary liver cancer is cancer that spreads to the liver from another part of the body.

Hepatocellular carcinoma is the most common liver cancer type. And, it typically begins in the primary liver cells (hepatocyte).

Anal cancer:

Anal cancer starts in the anal canal— a short tube at the end of your rectum through which stool leaves your body. Most anal cancers start from cells in the mucosa, which is the inner lining of the anal canal.

Squamous cell carcinoma is the most common type of anal cancer. Many types of tumors can develop in the anus, including non-cancerous ones.

Gallbladder & biliary tract cancer:

Gallbladder or biliary tract cancers are rare cancers usually diagnosed late due to lack of early signs and symptoms. It isn’t unusual for gallbladder cancer to be diagnosed only after the gallbladder is checked for gallstones or removed. The gallbladder is a small, pear-shaped organ located next to the liver. Its role is to store bile, a fluid that aids with digestion and fat absorption in the small intestine.

Biliary tract cancer (also known as cholangiocarcinoma) is cancer in the bile ducts (tubes that transport bile from the liver). Biliary tract cancer can form anywhere along the bile ducts.