The gastrointestinal (GI) tract is 25-foot-long pathway that extends from the mouth to the anus. Everything you eat passes through the esophagus and gets processed in the stomach and small intestines to extract nutrients. Ultimately, the waste is removed from your body through the colon and rectum. 

Sometimes, a tumor can form in one of these organs, after a change in the DNA causes abnormal cells to grow. What’s behind this kind of change (known as a mutation)? It could be anything from underlying conditions to lifestyle choices to genetics.

Gastrointestinal cancer is common, both in the United States and worldwide. Treatments are more effective when the cancer is detected at an early stage—which, unfortunately, can be a challenge.

“Colorectal cancers are the most common and most treatable GI cancers in the United States,” says Yale Medicine’s Jeremy Kortmansky, MD, a medical oncologist. “About 5 to 10 percent occur from an inherited genetic risk factor, but the remaining cases happen sporadically. Most of these cases are related to unhealthy behaviors.” 

The good news is that healthy lifestyle changes can help reduce the risk for GI cancer. “There is a clear reduction in risk with a lifestyle that includes regular exercise, a low-fat diet high in fruits and vegetables, minimal red meat, and moderate alcohol,” Dr. Kortmansky says.

Routine colorectal screening also markedly reduces the risk of colon cancer by finding and removing polyps before they have the chance to become cancerous, he says.

“We often consider the risk of colorectal cancer to increase with age,” says Dr. Kortmansky, “but recently, the incidence in patients under 50 is rapidly increasing. For this reason, the American Cancer Society recently recommended that routine colorectal cancer screening should start at age 45. It is important to catch colorectal cancers early, because if we do, they are highly curable.” 

The most common types of gastrointestinal cancers are as follows:

• Esophageal cancer
• Gastric (stomach) cancer
• Colorectal cancer
• Pancreatic cancer
• Liver cancer

Other types are much less common, including neuroendocrine tumors, gastrointestinal stromal tumors, and anal cancer.

Generally speaking, gastrointestinal cancers are more likely to develop in men, and the risk increases with age. Studies have linked these cancers to cigarette smoking, alcohol consumption and unhealthy diets.

Tumors may also result from specific underlying conditions. These can include gastroesophageal reflux disease in the esophagus, Helicobacter pylori infection in the stomach, hepatitis B or C virus infection or cirrhosis in the liver.

A small percentage of gastrointestinal cancers are inherited. 

Most of the time, symptoms of gastrointestinal cancers don’t occur until the tumor has become more advanced. Then, they depend on the type of cancer. Patients with esophageal cancer may have difficulty swallowing, whereas those with gastric cancer will notice ulcer-like symptoms (e.g., indigestion, loss of appetite, bloating and pain). Liver cancer and pancreatic cancer can also lead to abdominal pain, and colorectal cancer—as you might expect—causes changes in bowel function or bleeding.

If patients have symptoms and the doctor has reason to suspect a diagnosis of gastrointestinal cancer, they may perform some of the following tests:

• Endoscopy or esophagogastroduodenoscopy (EGD) to check the lining of the esophagus, stomach, and small intestine for tumors
• Colonoscopy to check the colon and rectum for polyps, which can become cancerous
• Lab tests to look for changes in the blood that could be signs of cancer
• Imaging studies (MRI, X-ray, ultrasound, CT scan or PET scan) to check for abnormal tissue anywhere in the digestive system. An endoscopic ultrasound (EUS) may be necessary. In this procedure, a doctor inserts an endoscope—a thin tube equipped with a light, camera, and ultrasound probe—into the patient’s mouth, down their throat, and into the stomach. The probe emits sound waves to produce an image of the tissues that make up the stomach wall and other nearby tissues. 
• Biopsy to obtain a sample of abnormal tissue and analyze it for the presence of cancer cells. Tissue samples are often collected during an endoscopy procedure. A pathologist then examines the tissue under a microscope to check for the presence of cancer cells.

When the tumor is easy to reach, surgery might be all that’s necessary. When it’s harder to reach or its removal would significantly affect gastrointestinal function, then chemotherapy, radiation therapy, or targeted therapy may be tried first. Some types of gastrointestinal cancers may be treated with targeted therapy (drugs that target specific components of the cancer cells) or immunotherapy (drugs that suppress or stimulate the patient’s immune system to help it better fight cancer).

Surgery involves complete removal of the tumor, along with surrounding tissue. To restore function of the esophagus or stomach, a procedure called anastomosis may be performed to connect the remaining healthy portions of the organ. Some liver cancer patients could be eligible for transplantation.

For very advanced cases of gastrointestinal cancer that can’t be effectively treated, doctors may aim to alleviate symptoms rather than cure the disease.

At Yale Medicine and the Yale Cancer Center, treatment of patients with colorectal cancer and all GI malignancies is a highly integrated endeavor. Detecting and treating these cancers takes a team, including gastroenterologists, specialized GI cancer surgeons, medical oncologists, radiation oncologists, clinical geneticists and nutritionists.

“Patients have the best results when they are treated by an integrated team with high-volume experience,” Dr. Kortmansky says. “Our team is focused specifically on GI malignancies and meets regularly to coordinate treatment plans. We confirm the diagnosis, review the imaging and map out options that include both standard therapies and clinical trials, and we counsel patients and their families. This approach and its availability throughout the Yale Cancer Center network is what makes it so special.”