Cancer Genetics Program

Cancer is a genetic disease, but it is not necessarily inherited. Cancer is caused by a combination of environmental and genetic influences, with the environment acting as the primary cause of cancer in some people. In some families, inherited abnormalities in cancer genes can increase the risk of cancer, or lead to multiple cancers. There are a variety of inherited cancer syndromes, the most common of which are hereditary breast / ovarian cancer and hereditary colon cancer. About 5-10 percent of breast & ovarian cancers and 5 percent of colon cancers are due to dominant genetic risk factors that can be inherited from a person’s mother or father.

Currently, there are two known genes, BRCA1 and BRCA2, that are responsible for the majority (approximately 85 percent) of hereditary breast and ovarian cancers. The normal function of these two genes is to help protect against the development of cancer. When there is a mistake, or mutation, in one of these genes this protection is no longer present. A woman who inherits a mutated BRCA1 or 2 gene has a lifetime breast cancer risk of 56-85 percent (compared with a risk of 12 percent in the average woman), and a lifetime ovarian cancer risk of 20-40 percent (compared with a general population risk of <2 percent). Additional breast/ovarian cancer susceptibility genes will undoubtedly be identified in the future. There are also some additional, rare heritable cancer syndromes that include an increased risk for breast cancer in addition to other cancer types. For both males and females, there is a slightly increased risk for pancreatic cancer in BRCA2 mutation carriers, for colon cancer in BRCA1 carriers, and male mutation carriers of either gene have an increased risk of prostate and breast cancer. Because of the increased risks of cancer, it is important that people who might carry a mutation in one of these genes receive accurate information about their cancer risk, and how to reduce it. Providing this information, and helping people in decision making, is one of the services provided to patients and families by genetic counselors.

Cancer screening recommendations for female BRCA1 or 2 mutation carriers are understandably much more intensive than for women in the general population. For example, annual mammograms along with annual breast MRIs and biannual clinician breast exams should begin at age 25-35 or 10 years earlier than the earliest cancer diagnosis in the family. This is compared to annual mammograms beginning at age 40 for women at average risk.

Annual transvaginal ultrasound and annual serum CA-125 measurements are recommended for ovarian cancer screening in BRCA1 and 2 carriers, although this form of screening has not been shown to prevent ovarian cancer. Management options for these high-risk patients may also include chemoprevention (tamoxifen, oral contraceptives) or prophylactic surgery (mastectomy, oophorectomy, or both). Surgery can dramatically reduce the risk of cancer in women who have inherited mutations in the BRCA1 or BRCA2 genes. Generally, BRCA1 or -2-associated ovarian cancer risk does not significantly increase until a woman is in her 40’s - typically after childbearing years, so many woman can complete their family before considering ovarian surgery.

Genetic testing is available for BRCA1 and BRCA2. Determination of whether a patient is an appropriate candidate for genetic testing includes assessing the likelihood of gene involvement as well as exploring the patient’s motivations for pursuing testing. A thorough discussion of the limitations of genetic testing, possible test results and the risks and benefits of testing is mandatory for each patient to ensure informed consent. This service is provided by a genetic counselor with expertise in cancer genetics.

The field of cancer genetics is relatively young, and many patients and physicians are unaware of the role of cancer risk assessment and education. A significant family history of breast (and ovarian) cancer is the primary indicator that a BRCA1 or BRCA2 mutation may be present in a family. This can sometimes be difficult to determine, however, especially if a family is small and/or if the affected relatives are on the paternal side.

Recognizing the importance of providing patients with access to cancer genetics services, Mercy & Unity Hospitals have partnered with Hubert H. Humphrey Cancer Center. Cancer genetic services at Mercy & Unity comprise cancer genetic counseling, provided by Denise Marty, MS, and a medical oncologist consultation with Thomas Amatruda, M.D., whose expertise includes establishing appropriate cancer surveillance regimens and other cancer preventive strategies with patients at high risk for cancer due to hereditary factors. Genetic counseling is appropriate when a family history is suggestive of a heritable predisposition for malignancy and includes collection and analysis of a family history, support counseling, education, and informed consent regarding genetic testing of DNA for cancer-causing mutations and DNA banking for future testing.

Denise Marty, MS
Genetic Counselor
Mercy/Unity Cancer Genetics Program

Thomas Amatruda, MD
Hematology/Oncology

High Risk program

Nurses in the Breast Diagnostic Center (763-786-9460), and the Breast Cancer Clinical Nurse Specialist (763-236-3657) are able to assist a woman in assessing her risk of breast cancer using the Gail and Claus Risk Assessment models. This program assigns risk based on family history, age, number of previous biopsies and other factors. The model is good for evaluating risk in women who do not have a genetic cancer. The Genetic Counselor is best prepared to analyze genetic risk. Following the risk assessment, patients can be referred to an oncologist or to their primary care physician for follow up.