The majority of patients who are diagnosed with early-stage breast cancer often have surgery performed without having a genetic test completed, or before testing for BRCA1/2 and other cancer genes has been implemented. While a genetic test is unlikely to yield a high-risk result for many women, a genetic test offers important information for the care of patients at high risk due to young age or strong family history.
A study published in the Journal of Clinical Oncology revealed that approximately one-third of surgeons rarely referred patients for genetic counseling; 73% of high-volume surgeons and 35% of lower-volume surgeons said they were confident in discussing genetic test results with their patients, says Allison Kurian, MD, MSc (Table).
These numbers can be perplexing given how much is known about the procedure. “A great deal is known, as we have been testing clinically for pathogenic mutations in two genes (BRCA1 and BRCA2, BRCA1/2) for more than 20 years,” says Dr. Kurian. “We have learned a lot about how to take care of patients who carry BRCA1/2 mutations. In the last few years, changes in genetic sequencing technology and regulation have made ithttps://www.physiciansweekly.com/wp-content/uploads/2018/03/genetic-testing-breast-cancer-Yao-table.png possible to test many more genes at much lower prices. Thus, we are acquiring more genetic information from more patients very quickly.”
In their study, Dr. Kurian and colleagues surveyed more than 2,500 women diagnosed with stage 0-II breast cancer in 2014-2015. Nearly two-thirds of those women surveyed (61%) reported that no genetic testing was performed. Of the sample size, only 26% underwent a genetic test, 72% said no mutation was found, 9% said a variation of uncertain significance was found, and 7% reported a high-risk mutation in BRCA1/2 or other risk-associated gene.
Benefits of Genetic Testing
“Genetic testing reads the sequence of a particular gene and determines whether there is an error that will incapacitate the gene; if there is, we call that error a ‘pathogenic mutation,’ which means that the gene does not function normally in the patient’s cells,” says Dr. Kurian. “These mutations are inherited from parents and passed on to children. When there is a pathogenic mutation in a gene that is involved in cancer prevention (eg, BRCA1/2, which normally prevent cells from acquiring genetic damage that may lead to cancer), then patients have much higher risks of developing certain cancers.”
The test also can determine whether a patient’s cancer has a strong hereditary cause, and can help to estimate her risk for future cancers (eg, a second breast cancer, an ovarian cancer, or another type) and the cancer risks of any of her relatives who carry the same pathogenic mutation. Pathogenic mutations are relatively rare (5% to 10% of breast cancer patients), but when present, they may change a patient’s decisions about surgery—including whether to consider surgical prevention of a second cancer through double mastectomy—or may change the medications offered to treat a patient’s cancer.
For all that is known about genetic testing, however, there is still a great deal of information that is evolving. Physicians must keep themselves and patients informed of these changes.
“Genetic sequencing and results interpretation are complex and evolving very quickly,” Dr. Kurian says. “It is difficult for clinicians who are not genetics specialists to keep up with all the new developments in terms of available tests, appropriate patient selection for testing, and the implications of results for treatment. It is also difficult for clinicians to explain all of this information in a way that patients can understand, which is why referring patients to a clinician with genetics expertise, namely a licensed genetic counselor, is very important when genetic testing is considered.”
Readings & Resources (click to view)
Domchek S, Bradbury A, Garber J, et al. Multiplex genetic testing for cancer susceptibility: out on the high wire without a net? J Clin Oncol. 2013;31:1267-1270.
Kurian A, Ford J. Multigene panel testing in oncology practice: how should we respond? JAMA Oncol. 2015;1:277-278.
Evans D, Wisely J, Clancy T, et al. Longer term effects of the Angelina Jolie effect: increased risk-reducing mastectomy rates in BRCA carriers and other high-risk women. Breast Cancer Res. 2015;17:143.
Noar S, Althouse B, Ayers J, et al. Cancer information seeking in the digital age: effects of Angelina Jolie’s prophylactic mastectomy announcement. Med Decis Making. 2015;35:16-21.