Genetic Testing

Between 5% and 10% of all cancers are hereditary, which means that changes (or mutations) in specific genes are passed from one blood relative to another. People who inherit one of these gene changes will have a higher risk of developing cancer at some point in their life. Genetic counseling can help people understand this risk.

Genetic counseling is not for everyone. In most cases, people who need genetic counseling fit into one of two groups.

Group one includes people who are cancer-free but, due to other medical conditions or family history, may have an increased risk for developing the disease. This includes people with:

• two or more close family members with the same type of cancer. For example, a mother and sister with breast cancer or a father and daughter with colorectal cancer.
• the same type of cancer in several generations of a family.
• Ashkenazi (Eastern or Central European) Jewish ancestry and family history of breast or ovarian cancer.
• polyposis, or multiple polyps in the stomach or intestines.

Group two includes people who have a cancer diagnosis and want to learn if it is genetic. Not everyone with cancer needs genetic counseling, though. Instead, it is usually recommended for patients who have:

• developed cancer at an earlier age than usual for their disease
• been diagnosed with two or more separate cancers
• developed a rare type of cancer, such as male breast cancer or medullary thyroid cancer
• family history of the same or related type of cancer
  

If you fit into one of these categories, it's a good idea to meet with a genetic counselor. 

About genetic counseling

The first step to understanding your genetic cancer risk is a genetic counseling session. There are several steps to these sessions.

Medical and family history review 

The genetic counselor will take your medical history, as well as a cancer-focused family tree going back generations. Based on this information, the counselor will discuss how your family’s cancer history may be hereditary and what that means for you.

Genetic testing discussion        

Genetic tests use a patient’s blood sample to look for genetic mutations that may lead to an increased risk for some cancers. After the medical and family history review, the counselor will discuss whether genetic testing is right for you. You will also cover the ethical and legal issues of genetic testing. If the counselor recommends genetic testing, you will be given information about the appropriate test or tests.

Cancer screening and prevention recommendations 

Based on your family history and/or genetic test results, you will discuss ways to reduce your cancer risk. This discussion may cover cancer screening strategies, chemoprevention or even preventive surgery. You also may be referred to a high-risk screening clinic for further discussion and long-term cancer screening and monitoring.

Referrals to clinical research trials and research registries

Patients are often given the chance to join clinical research trials and registries. These can improve cancer care in many ways. For example, they can help doctors understand cancer risk factors and learn what screening and prevention methods work best.