Genetic Testing Confusion Can Lead To Unnecessary Mastectomies: Study

New research suggests that more than half of all patients who undergo a double mastectomy in response to genetic test results, do not actually have the gene mutation that may place them at risk of breast cancer. 

In a study published last week in the Journal of Clinical Oncology., researchers with the Stanford University School of Medicine indicate that many doctors do not fully understand genetic testing and are interpreting the tests incorrectly for patients.

The research involved a population-based sample of patients with breast cancer diagnosed from 2014 to 2015, from registries in Georgia and Los Angeles. Patients were surveyed about their genetic testing experiences, including gene testing for BRCA 1 and BRCA 2 gene mutations. These mutations often indicate increased risk of breast cancer later on.

Many patients who discover BRCA 1/2 gene mutations opt for a double mastectomy to reduce their risk of cancer. BRCA 1/2 cancers account for five percent of all breast cancers and 50% of hereditary breast cancers.

More than 660 patients had genetic testing. Those with BRCA 1/2 gene mutations had the highest rate of double mastectomies. However, the surgery was also common among patients with genetic variants of “uncertain significance.”

Only about half of the patients spoke to a genetic counselor. Instead, they only had the conversations concerning specific genetic mutations with their primary care doctor.

While many surgeons became more skilled at interpreting testing results, most treated patients with pathogenic BRCA 1/2 mutations the same as those with the mutations that may have been less significant.

Researchers noted that half of patients with genetic variants of “uncertain significance” underwent a double mastectomy. These genes may not be “normal,” but researchers said they have a 90% chance of being harmless.

Many surgeons indicate they treat “uncertain” results as aggressively as a positive BRCA 1/2 test. Only seven to 10 percent of women who underwent testing discussed their results with multiple doctors or sought a second opinion.

An editorial published in the same journal highlighted the increase in genetic testing in recent years. Since the high profile genetic testing, and subsequent double mastectomies, of celebrities, such as Angelina Jolie, referral for genetic counseling rose by 90% in the first 6 months after Jolie’s surgery.

Overall, the number of BRCA1/2 carriers identified with genetic testing increased by 110%.

The editorial highlighted other studies which indicated many mutation carriers do not meet the criteria for testing because the incidence of cancer is rare in their family history. Patients who have mutations with “uncertain significance” can choose surgery or enhanced cancer surveillance and yearly MRIs.

Study authors highlighted the need to focus on appropriate testing, communication and counseling concerning genetic mutations. Treatment guidelines indicate women with results that show an “uncertain significance” should not be treated aggressively with double mastectomy surgeries.