Study: Genetic Testing Prior to Breast Cancer Treatment Influences Decisions about Preventive Measures on Opposite Breast (dateline May 4, 2004)
A new study finds that women who are diagnosed with breast cancer and receive genetic testing to determine their risk of developing cancer in the opposite breast are more likely to choose preventive treatment. Normally, women with breast cancer are given the option of genetic testing after their breast cancer surgery to determine whether they carry mutations of certain genes that put them at greater risk of developing breast cancer in the other breast. However, the current study suggests that performing genetic testing prior to breast cancer surgery can help women make informed decisions about preventive measures.
Women who test positive for genetic mutations of the BRCA1 (breast cancer gene 1) or BRCA2 (breast cancer gene 2) genes are at a higher than average risk of developing breast cancer. Over a lifetime, women with BRCA mutations have a 50% to an 85% chance of developing breast cancer. However, only around 5% of breast cancer cases are associated with BRCA gene mutations.
All women are born with BRCA genes. When functioning normally, BRCA1 and BRCA2 genes help repair damage to DNA-a process that also prevents tumor development. In 1994, researchers discovered that women who carry mutations of BRCA1 or BRCA2 are at higher risk of developing both breast and ovarian cancer than women who do not have these genetic mutations.
In the current study, Jeffrey N. Weitzel, M.D., of the City of Hope National Medical Center in Duarte, California, and colleagues performed genetic testing on 32 women with breast cancer prior to breast cancer surgery (mastectomy). Seven of the 32 women were found to BRCA gene mutations, putting them at high risk of developing breast cancer again.
Knowing their genetic test results prior to mastectomy, all seven women opted for the preventive removal of the opposite breast at the same time as their original mastectomy. Preventive, or prophylactic, mastectomy, though controversial, has been shown to greatly reduce the chances of developing breast cancer in the future.
Dr. Weitzel and his team conclude that knowledge of a genetic mutation prior to breast cancer surgery influences women's decisions about preventive options. However, the researchers question the feasibility of genetic testing prior to the original breast cancer treatment.
According to the Mayo Clinic, families that typically pass on BRCA defects have the following characteristics:
Genetic testing is a controversial subject, and healthcare professionals recommend seriously considering the consequences of knowing the test results before deciding whether genetic testing is appropriate. Advantages to genetic testing include feelings of relief, the opportunity to try new treatments or preventive measures targeted toward BRCA mutation carriers, and taking more aggressive breast cancer preventive and/or treatment options if test results are positive. Disadvantages to BRCA gene testing include increased stress if the results are positive, telling family members that they may also carry the mutations, and facing potential difficulties with insurance providers if the testing is not conducted anonymously. Women who are considering genetic testing for BRCA gene mutations are encouraged to discuss the decision with a genetic counselor before undergoing testing.