One of these hereditary conditions is Hereditary Diffuse Gastric Cancer (HDGC). Here are some common questions that are asked about HDGC and the answers but always consult with your healthcare provider for more information and for more specifics about your disease and situation.
What is Hereditary Diffuse Gastric Cancer?
Hereditary diffuse gastric cancer (HDGC) is an inherited condition associated with an increased risk of stomach (gastric) cancer. Diffuse gastric cancer is a specific type of stomach cancerthat tends to affect much of the stomach rather than staying in one area of the stomach. The average age for someone with HDGC to be diagnosed with stomach cancer is 38, although it can be diagnosed much earlier or later than that. Women with HDGC also have an increased risk of lobular breast cancer. People with HDGC may also have some increased risk of colorectal cancer.
What causes HDGC?
HDGC is a genetic condition. This means that the cancer risk and other features of HDGC can be passed from generation to generation in a family. The gene associated with HDGC is called CDH1. A mutation (alteration) in the CDH1 gene gives a person an increased risk of developing stomach cancer as well as other cancers associated with HDGC. Researchers believe that other genes may also be associated with HDGC, and studies are ongoing to learn more. Ask your healthcare provider about this or contact us at Debbie's Dream for more information.
How is HDGC inherited?
Normally, every cell has two copies of each gene: one inherited from the mother and one inherited from the father. HDGC can be passed from a parent to an offspring. HDGC follows an autosomal dominant inheritance pattern, in which a mutation happens in only one copy of the gene. This means that a parent with a gene mutation may pass a copy of their normal gene or a copy of the gene with the mutation to their offspring. Therefore, a child who has a parent with a mutation has a 50% chance of inheriting that mutation. A brother, sister, or parent of a person who has a mutation also has a 50% chance of having the same mutation.
How common is HDGC?
The overall incidence of gastric cancer varies in different parts of the world. In the United States, it is estimated that less than 1% of the population will develop stomach cancer. The highest rates of gastric cancer are found in China, Japan, and other countries in Southeast Asia, as well as in Central and South America. The specific number of families with HDGC is unknown but it is estimated that only approximately 1% of all stomach cancers are caused by a mutation in the CDH1 gene.
How is HDGC diagnosed?
Guidelines for the diagnosis of HDGC syndrome have been proposed, but may change over time as more is learned about this condition. Currently, the diagnosis of HDGC is suspected if a person or family members meet any of the criteria listed below:
- At least two cases of stomach cancer in a family, with at least one being diffuse gastric cancer and diagnosed before age 50
- At least three cases of stomach cancer at any age in a family, with at least one being diffuse gastric cancer
- A person diagnosed with diffuse gastric cancer before age 45
- A person diagnosed with both diffuse gastric cancer and lobular breast cancer
- A person diagnosed with diffuse gastric cancer and another family member diagnosed with lobular breast cancer
- A person diagnosed with diffuse gastric cancer and another family member diagnosed with signet cell adenocarcinoma of the colon
Genetic testing for mutations in the CDH1 gene is available. However, it is estimated that only about 30% of families that appear to have HDGC will have a mutation in the CDH1 gene. Therefore, both clinical and genetic aspects must be considered in counseling individuals about the potential for their family to have HDGC, and talking with a genetic counselor or geneticist (a doctor with training in genetic diseases and conditions) that is familiar with the syndrome is recommended.
What are the estimated cancer risks associated with HDGC?
In people who have a mutation in the CDH1 gene, the lifetime risk for advanced diffuse gastric cancer is estimated to be greater than 80% for men and women by age 80. Women with a mutation in theCDH1 gene have about a 60% risk of developing lobular breast cancer by age 80. There is also a higher risk of colorectal cancer in people with HDGC.
What are the screening options for HDGC?
Screening for stomach canceris suggested for people known to be at risk for HDGC. However, the effectiveness of current screening techniques for the early diagnosis of stomach cancer is not proven. Screening recommendations may also change over time as new technologies are developed and more is learned about HDGC. It is important to talk with your doctor about appropriate screening tests.
Current Screening Options:
- Endoscopy (also known as an upper gastrointestinal [GI] study; this procedure uses a thin, flexible tube with a light inserted into the body to examine a specific region)
- Chromoendoscopy (endoscopy using dye to help detect cancer)
- Endoscopic ultrasound(which uses sound waves to find a tumor in the body)
Additional Screening for Women:
Women at risk for HDGC should be considered at high risk for breast cancer and should talk with their doctor about breast cancer screening options at the age of 35, or ten years before the age of the youngest affected relative. Screening options include:
- Monthly breast self-examinations
- Clinical breast examinations (examination by a doctor or nurse) every six months
- Regular breast imaging with mammograms, ultrasound, and magnetic resonance imaging (MRI).
Colonoscopy, every one to two years, should be considered in families where both gastric cancer and colorectal cancer have been diagnosed. Colorectal cancer screening should begin five to 10 years earlier than the earliest diagnosis of colorectal cancer in the family or by age 50, whichever is sooner.
Questions to Ask Your Doctor
If you are concerned about your risk of cancer, talk with your doctor. Consider asking the following questions of your doctor:
- What is my risk of developing stomach cancer?
- What is my risk of developing other types of cancer?
- What can I do to reduce my risk of cancer?
- What are my options for cancer screening?
If you are concerned about your family history and think you or other family members may have HDGC, consider asking the following questions:
- Does my family history increase my risk of stomach cancer?
- Does my family history increase the chances of others in my family getting stomach cancer?
- Does my family history increase my risk of getting other types of cancer?
- Does my family history increase the chances of others in my family getting other types of cancer?
- Should I meet with a genetic counselor?
- Should other members of my family meet with a genetic counselor?
- Should I consider genetic testing?
- Should other members of my family consider genetic testing?