Hereditary or genetic breast cancer accounts for approximately 5 to 10 percent of all breast cancers diagnosed. Identifying individuals with a genetic predisposition to cancer can significantly affect their medical management.
Either parent can transmit a single damaged gene that predisposes their offspring to breast cancer. The presence of a gene mutation significantly increases the risk of cancer over one’s lifetime.
Approximately 80 to 90 percent of all hereditary breast cancers are caused by mutations in BRCA1 (Breast Cancer 1) and BRCA2 (Breast Cancer 2) genes. Both these genes exist in everyone and normally function to suppress tumor cell growth. When a mutation or abnormality is present in either gene, an individual is more likely to develop certain types of cancer, including breast, ovarian, and to a lesser degree, colon, prostate and pancreatic.
The following are associated with hereditary breast cancers:
Onset at less than 50 years of age
Cancers in both breasts
Ovarian cancer at any age
Breast and ovarian cancers in the same individual
Breast cancer in a male patient
Ashkenazi Jewish ancestry
Known BRCA1 or BRCA2 mutation in the family
Carriers of BRCA 1 and BRCA2 mutations have a 56 to 87 percent lifetime risk of developing breast cancer, in contrast to a 12 percent lifetime risk in the general population. The same mutation increases the risk of developing ovarian cancer to between 27 and 44 percent, as compared to a 1.4 percent risk in the general population. BRCA1 and BRCA2 mutations also increase the risk of second primary cancers. Patients with known BRCA mutations have a 12 to 20 percent risk of developing a contralateral (other side) breast cancer within five years of their first diagnosis. One’s personal and family history are extremely important in determining whether to be tested.
The following steps may be taken to manage the risks of developing hereditary breast and ovarian cancers:
· Increased surveillance: Monthly self breast exams, regular clinical breast exams and mammograms with ultrasounds and breast MRI. Transvaginal ultrasound and blood test for ovarian cancer, CA-125 every 6 to 12 months.
· Chemoprevention: Tamoxifen reduces the risk of breast cancer by 49 percent. Oral contraceptives reduce the risk of ovarian cancer by 54 percent.
· Preventative surgery: Bilateral mastectomy reduces the risk of breast cancer risk by 90 percent. Oophorectomy reduces the risk of ovarian cancer by 96 percent.
Most insurance companies will cover the cost of genetic testing if one’s personal and family history indicates the medical necessity. Patients are protected under HIPPA and legally may not be discriminated against because of a positive result.
For more information, call the Women’s Center for Breast Health
Page last updated on May. 21, 2009