Understanding genetic testing
Cancer is a disease of the genes. We know that some people are more at risk of developing breast cancer than others because of their personal history, family history or both. The Comprehensive Breast Center at Staten Island University Hospital can help you determine your risk factors and make informed decisions and can provide genetic testing when appropriate.
Sporadic vs. hereditary cancer
- Sporadic cancer—Most cancers develop due to genetic damage sustained over a lifetime. When genes acquire defects that impact the cells’ ability to grow and divide properly, tumors form. Cancers that occur due to genetic changes acquired over time are called sporadic. Approximately 70-80 percent of all cancers are considered to be sporadic.
- Family clusters of cancer—Cancer that occurs in families more often than would be expected by chance is considered a familial cancer cluster. Familial clusters have been reported for many types of cancer and are believed to be due to a combination of risk factors including inherited susceptibility, environmental factors, and chance.
- Hereditary cancer—Cancer that results from genetic changes that are passed on from one generation to the next is considered hereditary. Approximately 5-10 percent of all cancers fall into this category.
Genes associated with increased risk for breast cancer
A number of genetic defects are associated with hereditary breast cancer. These inherited genetic changes can result in an increased risk of developing the disease, but do not guarantee if or when cancer will develop. The most common of these are the BRCA1 (breast cancer gene 1) and BRCA2 (breast cancer gene 2) genes. Abnormalities in these genes account for approximately 80 percent of hereditary breast and ovarian cancer cases.
Having a risk assessment performed by a highly skilled genetic counselor can help to determine if genetic testing is appropriate for you. Individuals found to carry a genetic change will work closely with their doctors to establish an appropriate screening and management plan to reduce risks for developing certain types of cancer and to assist with early detection.
Deciding on genetic testing for breast cancer
Genetic testing should be considered for individuals at high risk of developing breast cancer. You might fall into this high-risk category if:
- You or a close relative developed breast cancer before age 45
- You have two or more close relatives with breast cancer on the same side of the family
- You have breast cancer in more than one generation in your family
- You have a personal and/or family history of ovarian cancer
- You have family members who have had pancreatic or early onset prostate cancer (diagnosed before age 50)
- You are of Ashkenazi (Eastern European) Jewish ancestry
- You have a relative who has a known alteration in a gene associated with hereditary cancer
The genetic counseling process
If you are considering genetic testing, you may have many complex questions and concerns you would like to discuss prior to moving forward. A genetic counselor can meet with you to address your concerns and determine whether your family history suggests the presence of a hereditary cancer syndrome.
The genetic counselor will collect a detailed cancer-focused personal and family history. Using this information the counselor will work with you to:
- Assess your risk for developing cancer
- Discuss the option of genetic testing when appropriate
- Review the risks, benefits, and limitations of genetic testing including:
- Accuracy of the test
- Implications of test results
- The turnaround time for results
- Financial aspects of the testing
- Concerns regarding genetic discrimination
- Provide you with educational materials and emotional support