Newly diagnosed breast cancer patients who test positive for BRCA1 and BRCA2 gene mutations are twice as likely as non-carriers to opt for a double mastectomy

Newly diagnosed breast cancer patients who test positive for BRCA1 and BRCA2 gene mutations are twice as likely as non-carriers to opt for a double mastectomy to reduce the risk of cancer in the opposite breast, according to the first large-scale study evaluating the impact of genetic counseling and testing on breast cancer treatment decisions.

An accompanying editorial discusses the increasing demand for genetic testing and the challenges associated with offering genetic counseling and testing to high-risk patients in the clinical setting. Both the study and editorial will be published online April 5 in the Journal of Clinical Oncology (JCO).

“Our study shows that genetic counseling and testing can have a significant impact on treatment decisions among high-risk breast cancer patients,” said Marc Schwartz, MD, associate professor of oncology at Georgetown University’s Lombardi Cancer and lead author of the study. “Given the high risk of contralateral breast cancer among BRCA1 and BRCA2 carriers, genetic counseling and testing should be available to interested high-risk patients, so that they can make informed decisions about treatment.”

Breast cancer patients with BRCA1 and BRCA2 mutations have a greatly elevated risk of developing cancer in the opposite breast – as high as 60% by some estimates – for at least 10 years following their original diagnosis.

Researchers at the Lombardi Cancer Center provided free genetic counseling to 167 patients newly diagnosed with breast cancer, with test results available in about two weeks. Thirty-one women tested positive for BRCA1 or BRCA2 mutations, while tests in the other 136 patients found no mutation or a mutation of unknown significance. Of those who tested positive for BRCA1 or BRCA2 mutations, 48% opted for an immediate double mastectomy, compared to 24% of women with no mutation or a mutation of unknown significance.

Researchers noted that many of the women who chose to have a double mastectomy despite negative genetic test results had either a strong family history of breast cancer or other risk factors, including multiple previous biopsies in the opposite breast.

Although a positive test result strongly influenced a woman’s treatment choice, a physician’s recommendation was the single most important factor affecting her decision.

“Patients whose physicians recommended that they undergo genetic testing or consider a double mastectomy were significantly more likely to choose the procedure – a finding that underscores the complementary role of genetic counseling and testing and shared decision-making between patients and physicians,” said Dr. Schwartz.

An accompanying editorial by Mary B. Daly, MD, PhD, a medical oncologist at the Fox Chase Cancer Center in Philadelphia, noted that the study “provides compelling evidence that, when given access to genetic risk counseling and testing services with no financial restraints, women at high risk for breast cancer are willing to undergo genetic testing and will incorporate the test information into primary treatment decisions.”

“Given the high rates of contralateral breast cancer in BRCA1 and BRCA2 mutation carriers, the choice to undergo a bilateral mastectomy rather than breast-conserving surgery could ultimately translate into improved survival for this population of patients,” she added.

In light of the study’s findings, Daly discussed the feasibility of providing genetic counseling and testing to patients, noting the financial and institutional barriers that may limit its widespread availability.

Despite increased access to genetic testing in the United States, patients still face significant delays in getting an appointment to see a genetic counselor and obtaining insurance approval. Daly noted that such delays are frustrating for early stage breast cancer patients who urgently want to initiate treatment. In addition, the high cost of genetic counseling and testing may not be covered by insurance – a situation that Daly said “restricts the ability to make timely and informed breast cancer treatment decisions to a privileged few.”

While rapid testing is available in some locations, patients still need to see a genetics counselor and obtain insurance approval, which can delay treatment decisions. Moreover, rapid tests are much more expensive than regular tests, and often not fully covered by insurance.

“Such barriers, however, should not deter the oncology community from encouraging widespread access to genetic counseling and testing for high-risk cancer patients, but rather should commit us to the elimination of these barriers,” Daly added.