Genetic tests for breast cancer patients create treatment opportunities — and confusion

The past decade has witnessed a rapid expansion of genetic tests, including new instruments to inform patients who have been diagnosed with breast cancer about the risk of recurrence and to guide their treatment.

But the clinical significance of many of the inherited mutations that can now be identified remains unclear, and experts are torn on when and how to deploy all the new tests available. Patients are sometimes left paying out-of-pocket for exams that are not yet the standard of care, and even the most up-to-date oncologists may be uncertain how to incorporate the flood of new information into what used to be standard treatment protocols.

A quarter-century ago, Myriad Genetics introduced the first breast cancer genetic test for BRCA mutations, two genes associated with a substantially elevated risk of getting breast cancer, opening the door to a new era in genetic testing. BRCA1 and BRCA2 mutations account for as many as half of all hereditary breast cancers, and people with a problematic mutation on one of those genes have a 45% to 72% chance of developing breast cancer during their lifetimes. They may also be at higher risk for ovarian and other cancers than people without harmful BRCA mutations.