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Gastric Adenocarcinoma and Proximal Polyposis of the Stomach (GAPPS)

What is gastric adenocarcinoma and proximal polyposis of the stomach (GAPPS)?  

GAPPS is a disease that affects the stomach, which is the organ that helps digest food. GAPPS causes many small bumps, called polyps, to form on the inside lining of the stomach. Polyps can be benign, meaning they cannot spread to other parts of the body. Polyps can also turn into cancer, meaning they can spread to other parts of the body. 

GAPPS can be difficult to diagnose because polyps often do not cause any symptoms. Polyps can also be caused by more common diseases too. GAPPS is different than other types of stomach cancer because it grows in a specific part of the stomach. GAPPS is a newly discovered type of hereditary gastric cancer syndrome, which means this disease runs in families.

How common is GAPPS?

GAPPS is a rare hereditary gastric cancer syndrome. Hereditary gastric cancer syndromes make up 1-3% of all stomach cancer cases. Because GAPPS is rare and relatively new, it is not known how many people actually have it. 

How is GAPPS diagnosed?

Some people with GAPPS have symptoms, but others don’t. Some people may feel pain in the area around the stomach. For people without symptoms, GAPPS can be discovered if the person has an imaging test for another reason.

Imaging: Your doctor will use imaging such as endoscopy to look at the inside of the stomach to check for signs of GAPPS. 

Biopsy: To check if you have GAPPS, your doctor will do a biopsy, taking a small sample from the polyps in the stomach with a needle. An expert, called a pathologist, will study cells from the sample under the microscope to see if the polyps have turned into cancer. 

How is GAPPS treated?

Treatment for each patient will be unique. You should go to an expert in stomach cancer treatment to decide the best approach for you. You can contact MyPART for help finding experts near you.

Treatment options to discuss with your doctor include: 

Watch and wait: In some cases, GAPPS grows very slowly and the polyps are benign (not cancer). In this case it may be safe for your doctor to monitor you regularly without treating it.

Surgery: Once GAPPS is diagnosed, you may need to have surgery to remove the stomach. It is recommended to have the stomach removed in cases where the polyps have turned into cancer. 

Does GAPPS run in families?

Yes, GAPPS runs in families. Genetic testing is recommended for all close relatives of people with GAPPS. Parents have a 50% chance of passing on GAPPS to their children. It is possible to test for GAPPS with a blood test. There is a test available which tells which family members are at risk for GAPPS and which are not.

How does GAPPS form?

Because GAPPS runs in families, we know that changes in a specific part of the APC gene are important in GAPPS. Not all people who have changes in the APC gene develop GAPPS the same. Some people may develop GAPPS later in life than others. It is important to continue going to your doctor to monitor the development of GAPPS.

What is the prognosis for someone with GAPPS?

The estimate of how a disease will affect you long-term is called prognosis. Every person is different and prognosis will depend on many factors, such as if cancer has developed from the polyps or if the cancer has spread to other parts of the body. 

If you want information on your prognosis, it is important to talk to your doctor. Also, NCI has resources to help you understand cancer prognosis

Doctors estimate survival rates by how groups of people with GAPPS have done in the past. Because there are so few GAPPS patients and each patient’s case is different, it is difficult to determine survival rates. The survival rate for patients with GAPPS that has spread to other parts of the body is lower than patients who do not have cancer that has spread to other parts of the body. On the other hand, family members with GAPPS who have had their stomach removed and where polyps have not developed into cancer yet have no further risk of stomach cancer. The overall 5-year survival rate for all stomach cancers is about 32%. 

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