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Hereditary Diffuse Gastric Cancer (HDGC)
An estimated 1 percent to 3 percent of cases of gastric cancers are hereditary diffuse gastric cancer (HDGC), an inherited cancer syndrome that leads to an increased risk for both diffuse gastric cancer and lobular breast cancer. Patients who inherit the genetic mutation for HDGC are at high risk for developing gastric cancer at a young age.
Diffuse Gastric Cancer
HDGC results in a cancer marked by the appearance of signet-ring shaped cells in the lining of the stomach, which occurs either one by one or in small clusters (a formation known as diffuse). The diffuse type of gastric cancer associated with HDGC is difficult to diagnose because the cancer is not visible on upper endoscopy (a procedure that uses a small camera to see into the stomach). For this reason, most cases of diffuse gastric cancer are diagnosed at late stages.
Identification of HDGC Family Members
People from HDGC families are at an increased risk of developing diffuse-type gastric cancer. It is estimated that the lifetime risk of developing gastric cancer is 80 percent. Additionally, female carriers have an estimated 60 percent lifetime risk of developing lobular breast cancer.
Hereditary diffuse gastric cancer is diagnosed in families with:
- Two or more cases of diffuse gastric cancer in first- or second-degree relatives, where at least one case was diagnosed before the age of 50, OR
- Three or more cases of diffuse gastric cancer in first- or second-degree relatives, regardless of the age at diagnosis
Among families that fit this criteria, it is estimated that 25 percent to 40 percent will have a CDH1 gene mutation.
Families with multiple cases of diffuse gastric cancer, as well as patients diagnosed with diffuse gastric cancer before age 40, are referred for genetic counseling and testing for CDH1 gene mutations.
Gastric Cancer CDH1 Screening
Patients from HDGC families, as well as patients diagnosed with diffuse gastric cancer before age 40, are referred for genetic counseling and testing for CDH1 gene mutations. They should also be followed by a medical team.
The current screening recommendations are upper endoscopy with biopsies on an annual basis. Because hereditary diffuse gastric cancer is nearly impossible to detect at an early stage, however, the recommended procedure to prevent gastric cancer is a total gastrectomy, or complete removal of the stomach. Although this procedure is complicated and commonly leads to weight loss, diarrhea, altered eating habits and vitamin deficiency, it is possibly the only method to prevent stomach cancer.
Screening at Johns Hopkins
Those with hereditary diffuse gastric cancer are at high lifetime risk for the development of gastric cancer that occurs at a young age. In addition, these patients are at increased risk for other cancers, including breast cancer. The disorder is caused by mutation in the CDH1 gene. Our Cancer Risk Assessment Clinic evaluates patients and families for this disorder, provides management recommendations and when appropriate, genetically tests patients for a CDH1 gene mutation.
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