On Cancer: Genetic Counseling and Genetic Screening for Cancer

Some people are genetically predisposed to developing certain types of cancer because they have a genetic mutation inherited from one of their parents — or sometimes both parents. These people have a higher risk of developing the disease than those in the general population.

If you have a family history of cancer, physicians and genetic counselors at Memorial Sloan-Kettering are available to help you understand your risk of developing cancer.

We spoke with genetic counselor Megan Harlan Fleischut about genetic counseling and testing and about the services offered by experts on our Clinical Genetics Service.

What percentage of cancers are inherited?

While all cancers are caused by genetic changes (mutations) in tumor cells, most cancers are not hereditary. Only about 5 to 10 percent of cancers — including breast, ovarian, colorectal, and prostate — are thought to be inherited, meaning that they are due to gene mutations passed down in one’s family.

What do we know about the link between inherited genetic mutations and cancer?

With some cancers, there are known mutations for which we can screen patients. Two of the most well known are mutations in genes called BRCA1 and BRCA2. These mutations have been linked to some, but not all, hereditary cases of breast and ovarian cancer as well as other cancers.

For cancers for which no tests are currently available, family history is the strongest risk factor.

Our laboratory investigators are working to identify previously unknown hereditary mutations that may predispose people to developing these and many other types of cancer. We are also performing genetic epidemiologic studies to explore how such mutations may contribute to disease in families and in populations.

If someone has a few relatives with cancer, should he or she consider genetic counseling?

Genetic counseling may be useful for you if you answer yes to any of the following questions:

• Have you or a close relative been diagnosed with cancer at an early age?
• Do you have more than one blood relative with the same type of cancer? If yes, is the same type of cancer found in more than one generation?
• Has anyone in your family had more than one type of cancer, not counting basal cell or squamous cell skin cancers?
• Some organs, such as the breast, kidney, and eye, come in pairs. Has anyone in your family had cancer on both sides of a pair of organs?
• Are you related to someone who is known to have an inherited mutation that can cause cancer?

Genetic counseling is typically recommended for individuals who are diagnosed with cancer at a very young age and for families with multiple cases of cancer. If you are interested in learning about your hereditary risk for cancer, we encourage you to schedule an appointment with us.

What happens during genetic counseling?

Your initial genetic counseling session will focus on your or your family's risk for cancer. We will tell you about the scientific concepts that relate to genetic testing to help you decide which genetic tests, if any, might be useful for you. Our goal is to provide clear and relevant information about genetic risk factors in a supportive and educational environment.

As part of a genetic counseling session, you will have the opportunity to ask questions and discuss many topics including your individual cancer risk assessment, personalized cancer screening recommendations, and options for participating in research taking place at Memorial Sloan-Kettering.

How should a person decide whether to have genetic testing?

Genetic testing is not the right choice for everyone. Your personality, your coping style, and your family's experience with cancer may influence your decisions about whether to have a genetic test.

For many people, a cancer risk assessment can be provided through genetic counseling alone, without the use of genetic tests. However, in some cases, genetic testing may help you and your physician make important decisions about your medical care.

What can a person do if they are at higher risk of developing a certain cancer or cancers?

If there is a history of cancer in your family, we recommend you undergo regular cancer screening, regardless of whether you have received genetic testing. The goal of screening is to prevent cancer or to find the disease at an early stage, increasing the chance that it can be treated. Screening may include colonoscopies for colorectal cancer and prostate-specific antigen (PSA) tests for prostate cancer. You may also wish to enroll in our Special Surveillance Breast Program, which provides services for the prevention and early detection of breast cancer.  

Our doctors and genetic counselors are available to discuss other options that may be available to you, including preventive surgery such as removal of the breasts or ovaries.

In addition, you may be able to participate in a clinical trial focusing on the study of hereditary cancers. Most of our protocols are registries or long-term follow-up studies to learn more about individuals with a family history of cancer. For example, you and your family members may also be able to enroll in a registry that tracks families who are affected by certain kinds of cancer.

How can someone make an appointment to speak with an expert in the Clinical Genetics Service?

For more information about Memorial Sloan-Kettering's Clinical Genetics Service and to schedule a consultation, please call us at 646-888-4050.