Hereditary diffuse gastric cancer

Up to 10% of stomach cancer cases are "familial" in origin, meaning that in about 1 in 10 cases, other family members are affected or have an increased risk. However, the exact cause for familial stomach cancer is not always known. While specific gene changes (mutations) have been found in a subset of people with stomach cancer, the genetic factors involved in this condition are still poorly understood.^[1] Shared environmental factors, or a combination of genetic and environmental factors, may be responsible for some familial cases of stomach cancer.

Known hereditary conditions that cause a genetic predisposition to developing stomach cancer (and sometimes other cancers) include:

• Hereditary diffuse gastric cancer
• Hereditary nonpolyposis colorectal cancer (also called HNPCC, or Lynch syndrome)
• Li-Fraumeni syndrome
• Familial adenomatous polyposis
• Peutz-Jeghers syndrome^[1]

These conditions are inherited in an autosomal dominant manner. However, not all people with a genetic predisposition to develop stomach cancer (or a known hereditary cancer syndrome) will develop stomach cancer.

Genetic testing can be done to look for the gene mutations that can cause some inherited cancer syndromes.^[2] People interested in genetic testing are encouraged to speak with a genetic counselor to discuss their medical and family history, and whether genetic testing in their case would be available and informative.

It has been estimated that 1% to 3% of cases of stomach cancers are hereditary diffuse gastric cancer (HDGC).^[3] However, the overall incidence of stomach cancer varies in different parts of the world. In the United States for example, it is estimated that less than 1% of the population will develop stomach cancer of any kind.^[4]

Whether HDGC should be suspected in a person or family depends on a number of criteria, based on the most recent guidelines from 2015. The criteria can be viewed here, and the full text article containing all of the updated clinical guidelines for HDGC can be viewed here.

In the United States, the Health Insurance Portability and Accountability Act (HIPAA) ensures that you are entitled to information in your medical record and under certain conditions, someone else's records. According to HIPAA, you may request records of a deceased person if you are related to a deceased person and certain information in that person's medical file relates to your own health.

In general, records stay where they are created unless state or federal laws or regulations require something else. If a doctor is part of a practice, the records belong to the practice according to the American Medical Association.

To find a medical record for a deceased family member:

• If the patient had health insurance at the time of care, contact the health plan to ask about medical records.
• If you know the doctor or place where treatment was provided, but you don’t have contact information, check a physician or hospital directory at a public library or on the Web, or ask a librarian to help you find contact information.
• If you don't know a physician’s name, another one of the patient's physicians may have copies of medical records.
• If you know the name of the medical practice where a doctor worked, ask the practice about records.
• If a hospital or medical center closed, contact the county, state or regional health department, or state hospital association to ask if the records are available. Some hospitals merge or are under new network ownership; try contacting the health care network that last owned the hospital.

Institutions may have standard forms you need to submit to get medical records. You also may need to get your identity certified to request and receive medical records. Include, if possible, in your request for medical records:

• Details about your identity, including your relationship with the patient
• Dates of service in question and place(s) of treatment
• Patient's date and place of birth
• Names of patient's parents
• Name(s) of patient's doctor(s)^[5]

People outside of the United States trying to locate medical records for a deceased family member may also find the above suggestions useful. However, we recommend contacting the department of health in your country for specific regulations and suggestions.

Yes. For reasons that are poorly understood, people with blood group type A have a higher risk of developing stomach cancer.^[6] People with blood group A have been known for decades to show an approximately 20% excess of gastric cancer than those of group O, B, or AB. They also show a similar increase in the rate of pernicious anemia. Some data suggest that group A may be particularly associated with diffuse gastric cancer. However, it is possible that the associations seen are not due to the blood group antigens themselves, but to the effects of genes closely associated with them.^[7]

You can read about additional risk factors for stomach cancer on the American Cancer Society's Web site.

People with a personal and/or family history of cancer with features suggestive of hereditary cancer can speak with a genetic counselor or geneticist who specializes in cancer risk assessment.

Features that suggest hereditary cancer may include:

• unusually early age of cancer onset
• multiple primary cancers in one person
• bilateral cancer in paired organs (such as breasts or kidneys) or multifocal cancer (more than one tumor arising from a single tumor)
• the same type of cancer appearing in multiple close relatives
• cancers in multiple generations
• rare types of tumors
• unusual occurrence of cancer (such as male breast cancer)
• rare cancers associated with birth defects^[8]

A genetic counselor or geneticist can evaluate a person's medical and family history, discuss whether genetic testing would be appropriate, explain the implications of a positive or negative test result, and address questions and concerns. They can also recommend options for screening and management of cancer risk (such as risk-reducing strategies).

The National Cancer Institute (NCI) Cancer Genetic Services Directory lists medical specialists who provide services related to cancer genetics, including cancer risk assessment, genetic counseling, and genetic testing for hereditary cancer syndromes.

You may also ask your doctor for a referral, or use one of the following online resources to find a genetics professional in your community:

• GeneTests offers a searchable directory of U.S. and international genetics and prenatal diagnosis clinics.
• The National Society of Genetic Counselors provides a searchable directory of US and international genetic counseling services.
• The American College of Medical Genetics has a searchable database of US genetics clinics.
• The American Society of Human Genetics maintains a database of its members, which includes individuals who live outside of the United States. Visit the link to obtain a list of the geneticists in your country, some of whom may be researchers that do not provide medical care.