Overview of Gastrointestinal (GI) Cancers
What is gastrointestinal cancer?
Gastrointestinal (GI) cancer is a term used for the group of cancers that affect the gastrointestinal tract and other organs that are contained within the digestive system, including the esophagus, pancreas, stomach, colon, rectum, anus, liver, biliary system, and small intestine.
Anal cancer starts in the anal canal--a short tube at the end of your rectum through which stool leaves your body. The inner lining of the anal canal is the mucosa. Most anal cancers start from cells in the mucosa. Anal cancers that start from cells in the glands located under the mucosa are called adenocarcinomas. Many types of tumors can develop in the anus, including non-cancerous ones.
Colorectal cancer starts in the colon or the rectum. These two cancers are often grouped together because they share many similar features. Most colorectal cancers begin as small, noncancerous (benign) clumps of cells, called polyps, on the inner lining of the colon or rectum. Regular screening is recommended for prevention since polyps don’t usually produce symptoms.
A cancer that occurs in the esophagus -- a hollow, muscular tube that connects the throat to the stomach. 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.
Gallbladder & Biliary Tract Cancer
Gallbladder cancer occurs when malignant cancer cells form in the tissues of the gallbladder. 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 that occurs in the bile ducts (tubes that transport bile from the liver). Biliary tract cancer can form anywhere along the bile ducts.
Gastrointestinal Stromal Tumors (GIST)
GISTs start in special cells, called interstitial cells of Cajal (ICCs), located in the wall of the gastrointestinal (GI) tract, also known as the digestive tract. ICC cells are part of the autonomic nervous system--the part of the nervous system that regulates body processes such as digesting food. The most common sites for GISTs are the stomach and small intestine.
Liver cancer starts in the cells of the liver. 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 actually start in the liver are considered liver cancer (called primary liver cancer). Hepatocellular carcinoma, which begins in the main type of liver cell (hepatocyte), is the most common type of liver cancer.
Cancer that begins in the tissues of the pancreas -- an organ that sits behind the stomach. It releases enzymes that help digest foods (especially fats) and hormones that help control blood sugar levels. The pancreas has two types of cells--exocrine and endocrine--which form different types of tumors.
Stomach cancer, also called gastric cancer, starts in the stomach. While stomach cancer can develop anywhere in the organ, most stomach cancers develop in the mucus-producing cells of the stomach’s inner lining. 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). Because the small intestine is made up of many different types of cells, different types of cancer can start there. There are four major types of small intestine cancers, which include adenocarcinomas, carcinoid tumors, lymphomas, and sarcomas. Small intestine cancer often begins with non-cancerous polyps, which over time, can change into cancer.
What are the risk factors for GI cancers?
Risk factors for gastrointestinal cancers vary among the different types. Some known general risk factors may include:
- Physical inactivity
- Heavy alcohol use
- A family history of GI cancer
- Having an inherited gene mutation that is known to increase your risk
- History of other conditions such as type II diabetes, inflammatory bowel disease (IBS), Crohn’s disease, chronic acid reflux, cirrhosis, and chronic viral hepatitis B or C
What are the symptoms of GI cancers?
Symptoms of GI cancers can vary depending on the type of cancer. Some warning signs may include the following:
- Abdominal pain
- Change in stool color
- Blood in the stool
- Jaundice (yellowing of the skin and whites of the eyes)
- Unexplained weight loss
- Feeling bloated
- Problems swallowing
- Loss of appetite
Are GI cancers preventable?
Cancer prevention is action taken to lower the chance of getting cancer. While there is no guarantee that you will not develop cancer, there are steps you can take to protect yourself. Making positive lifestyle changes (avoiding controllable risk factors) and visiting your doctor regularly for preventative screening are ways you can help lower your risk.
What should I ask my doctor about GI cancers?
Some important questions you may want to ask your doctor may include:
- What GI cancers can I be screened for? When and how often should I be screened?
- I have a family history of GI cancer. Should I consider genetic testing or screening at an early age?
- If I am diagnosed with a type of GI cancer, should my family members consider genetic testing or earlier screenings?
- What tests are done to determine if I have a GI cancer?
- What treatment options are available for my specific type of GI cancer?