Genetic test use rises in young US breast cancer patients

By Lynda Williams, Senior medwireNews Reporter

BRCA testing is becoming more common in women diagnosed with breast cancer by the age of 40 years in the USA, research shows, with concerns about genetic risk influencing surgical decisions.

In all, 87.0% of 897 women participating in the Helping Ourselves, Helping Others: Young Women's Breast Cancer Study between 2006 and 2014 had undergone BRCA testing within a year of diagnosis. The rate of testing rose significantly, from 76.9% of 39 patients diagnosed in 2006 to 96.6% of 146 patients in 2012 and 95.3% of 129 patients in 2013.

It is "reassuring" that women in the cohort are being tested in line with the recommendations of the National Comprehensive Cancer Network (NCCN) guidelines for women under the age of 50 years, write Ann Partridge (Dana-Farber Cancer Institute, Boston, Massachusetts, USA) and co-authors in JAMA Oncology.

But they question the generalisability of their findings, noting that the "high frequency of BRCA testing likely reflects the fact that most women enrolled in our cohort were insured, educated, and treated at cancer centers where comprehensive genetic counseling and testing services are widely available."

The team reports that women who were tested for the BRCA1 and BRCA2 mutations were significantly younger at diagnosis than those who did not, at 35.3 versus 36.9 years.

In all, 29.8% of 831 patients responded on the survey that their knowledge or concern about genetic risk had influenced decision-making about surgery.

Bilateral mastectomy was chosen by 86.4% of 88 women who tested positive for a mutation compared with 51.2% of 160 patients who did not carry a mutation, a significant difference. And patients who carried a BRCA mutation were significantly more likely to have undergone salpingo-oophorectomy than noncarriers (53.4 vs 2.5%).

Genetic risk was less influential on decision-making for chemotherapy, ovarian suppression and endocrine treatment in patients with and without a positive BRCA test.

Almost a third (31.6%) of the 117 patients who did not undergo BRCA testing said they had not discussed the possibility of a mutation with a physician or genetic counsellor; 23.9% of untested patients said they did not believe they were at risk and a similar proportion stated their physician felt they were not at risk.

Writing in an accompanying editorial, Jeffrey Weitzel, from City of Hope in Duarte, California, USA, and co-authors say this explanation for non-testing is "disconcerting" given that the NCCN guidelines on testing were available from the onset of the Young Women's Breast Cancer study, and emphasize the need for an explanation of genetic testing at diagnosis.

"Comprehensive GCRA [genetic cancer risk assessment] also addresses the challenges of conveying complex, uncertain or uninformative test results in a way that reduces confusion and uncertainty about risk management decision-making", they write.

Other reasons cited for not undergoing testing included concerns about insurance or work (12.8%) or cost (11.1%); however, 36.8% of untested women were considering genetic analysis in the future.

The editorialists conclude: "The task remains to ensure that the benefits of GCRA reach more individuals and families, including those among underrepresented minorities, with economic disparities, and in low- to middle-income countries.

"As long as there are growing communities of practice and research collaboration, it won't take another 20 years to get there."

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