Stomach cancer develops when malignant cells begin to grow somewhere in the five layers that form the stomach lining. Most stomach cancers start in the innermost layer, the mucosa, which contains glands that produce stomach acid and enzymes to aid digestion. Called adenocarcinomas, these account for the majority of stomach cancers. 

If you or a loved one have stomach cancer and come to Yale Medicine, you will be seen by a team of cancer specialists who work collaboratively to plan treatment. Our team includes radiation oncologists who can administer external beam radiation therapy, a method in which a machine aims high-energy X-ray beams at the tumor area.

Early-stage stomach cancer often doesn’t cause noticeable symptoms. As the disease progresses, though, patients may experience the following symptoms:

• Bloating: Feeling that the stomach is bloated or very full, even after a small meal, may be a sign that a tumor is obstructing part of the stomach.
• Abdominal pain: General pain in the stomach region with no known cause is a common sign of stomach cancer.
• Unintended weight loss: Trouble eating, loss of appetite, and nausea are symptoms that can lead to unintentional weight loss and should be brought to a doctor's attention.
• Nausea and vomiting: A more dramatic presentation of abdominal pain, bloating, and discomfort may include vomiting, potentially even vomiting blood.

An important point to remember is that these symptoms are also relatively common signs of noncancerous conditions, such as an ulcer or infection. On their own, or even in combination, they do not necessarily mean someone has stomach cancer. But anyone with such symptoms should see a doctor, so that a proper diagnosis can be made and, when needed, treatment can start as soon as possible.

A patient is likely to first see a gastroenterologist, who specializes in conditions of the gastrointestinal (GI) tract. The first step in diagnosing stomach cancer is to rule out another condition such as an ulcer that the symptoms may be signaling. The doctor may order blood tests to check for such conditions as anemia.

The doctor may also order imaging tests such as a CT (computerized tomography) scan, which allows doctors to see a tumor mass in the stomach. They may also order an endoscopy, in which a scope with a camera on the end is inserted down the esophagus and into the stomach to view the stomach’s interior.

If a tumor is observed during an endoscopy, a biopsy may be performed via the endoscope. A pathologist will look at the extracted tissue sample under a microscope to determine whether cancer cells are present.

Early-stage cancer may be treated via surgery alone. Such surgery involves removing a portion of the stomach along with the tumor.

For more advanced cancers, chemotherapy or radiation therapy may be used. The most common course of action is chemotherapy to kill off cancer cells in the stomach and beyond, followed first by surgery to remove the tumor and then another course of chemotherapy. Radiation therapy may also be used post-surgery to kill any cancer cells remaining in the tumor area. External beam radiation therapy is typically used, a method in which a machine aims high-energy X-ray beams at the tumor area.

In cases where surgery isn’t possible due to the patient's health or the size of the tumor, external beam radiation may be an alternative.

Every stomach cancer patient at Yale Medicine is seen by a team of cancer specialists. This team consists of a medical oncologist, a radiation oncologist, a gastroenterologist, and a surgeon, all of whom are trained to provide the highest levels of care possible. This team of experts works collaboratively to plan each patient's treatment.

Additionally, Yale Medicine patients benefit from clinical trials that test the latest, most innovative targeted cancer therapies. These include new chemotherapy regimens and the most up-to-date radiation therapy available in the region.