Lack of Understanding of Genetic Breast Cancer Testing

Kate Johnson

April 24, 2017

A lack of understanding among clinicians about genetic information is contributing toward the unnecessary use of bilateral mastectomies (BLMs), say researchers.

"A busy cancer doctor's major challenge is to test the right patient for the right genes soon enough to guide time-sensitive treatment decisions such as BLM," say the researchers, led by Allison Kurian, MD, from Stanford University School of Medicine, in California.

However, this "will require expanding the genetic counselor workforce and new strategies to integrate counseling more efficiently into the rapid pace of treatment decision making."

Dr Kurian and colleagues report their findings in a study published online April 12 in the Journal of Clinical Oncology.

As many as half of the surgeons who manage breast cancer patients' genetic test results make no distinction between those who have pathogenic mutations vs those who have variants of uncertain significance (VUS) in their BRCA1 or BRCA2 genes, they found.

This finding "reinforces the urgent need to improve both surgeons' and patients' genetic knowledge," Dr Kurian and collegues comment. "It is essential that patients understand the meaning of their results and that BLM be discussed with mutation carriers but not recommended for women with negative or VUS results."

In an accompanying editorial, Soojin Ahn, MD, and Elisa R. Port, MD, from the Mount Sinai Health System in New York City, write, "Providers who are not well versed in VUS literature may have difficulty with fully understanding the implications of a VUS result and misguide the patient.

"Because most VUSs are ultimately reclassified as benign, the management of an individual who carries a VUS should be based on personal and family history and not on the presence or absence of the variant itself," they add.

With new technology and less restrictive patents, there is a growing need for physicians to engage with breast cancer patients about genetic testing, Dr Kurian and her colleagues point out.

Study Details

The study used the Surveillance, Epidemiology, and End Results databases from Georgia and Los Angeles County to identify 3672 women who were diagnosed with breast cancer staged 0 to II from 2014 to 2015.

The patients and their attending surgeons were mailed separate surveys about 2 months after the diagnosis. The surveys contained questions about the patient's genetic testing, counseling, results, and treatment.

A total of 666 patients and 377 surgeon respondents were eligible for inclusion.

Not surprisingly, the results showed that women with pathogenic BRAC1/2 mutations underwent BLM at the highest rate: 80% of higher-risk women (determined on the basis of a predetermined list of personal and family history factors), and 85% of average-risk women.

However, women with VUS also underwent BLMs at high rates (43% and 51%, respectively). And even women with no BRCA1/2 mutations underwent BLM (34% and 42%, respectively).

Half of surgeons with a lower volume of breast cancer patients (20 or fewer breast cancer patients last year) and one quarter of higher-volume surgeons (>51 patients) reported managing patients with BRCA1/2 VUS the same way as they managed patients who carried BRCA1/2 mutations. Additionally, "fewer than half of surgeons offered breast-conserving therapy to some BRCA1/2 mutation carriers (43% of higher-volume, 25% of moderate-volume, and 36% of lower-volume surgeons)," the researchers report.

Regarding genetic counseling, "up to one third of surgeons rarely referred patients for genetic counseling and ordered testing without referral," they write. "Adequate pretest counseling may have been provided by other means, but this raises the possibility that only one in five patients received optimal pretest care. Of particular concern, lower-volume surgeons were least likely to refer to genetic counseling even though they were least confident about discussing testing" (35% of low-volume surgeons reported confidence in discussing testing compared to 73% of those with higher volume).

Asked by Medscape Medical News to comment on the study, Diana Eccles, MD, professor of cancer genetics at the University of Southampton, United Kingdom, said the findings "illustrate the point about how alarming indiscriminate genetic testing can be in vulnerable patients already struggling to cope with a real diagnosis of cancer.

"I am not sure what the BLM rate in the USA is these days, but 34% in noncarriers is really excessive," she added, noting that surgeons' frequent failure to discuss breast-conserving surgery with patients and offering patients with VUS the same treatment as those with pathogenic variants "reflects (a) a lack of training, and (b) a disconnect between the purpose of the test and the application of the result in a given clinical context."

As a general observation, she said "the falling cost of testing has increased access, but the cost will undoubtedly stack up downstream in the form of inappropriately excessive surgery ― not only for the patient with breast cancer but potentially for her perfectly healthy relatives."

Another expert who was approached for comment said the results did not surprise him. Elias Obeid, MD, MPH, from the Department of Clinical Genetics, Fox Chase Cancer Center, Philadelphia, Pennsylvania, suggested it is likely that both patient and physician factors are at play.

"This is a multifactorial problem that is not only related to information, interpretation, and understanding of genetic test results by both patients and providers but also fears about cancer and decisions that may be related to the diagnosis itself," said Dr Obeid.

"We have to keep in mind that patients in this study were all diagnosed with breast cancer. It would be interesting to see whether the results would be any different had there been two groups: women with breast cancer and women without breast cancer, all getting the same genetic testing, to see how much the fear from a cancer diagnosis drives such a decision about risk-reducing bilateral mastectomy," he said.

The authors of the study have disclosed a number of relationships with pharmaceutical companies, which are described in the original article. Dr Eccles occasionally consults for AstraZeneca concerning BRCA testing. Dr Ahn, Dr Port, and Dr Obeid have disclosed no relevant relationships.

J Clin Oncol. Published online April 12, 2017. Full text, Editorial

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