The Crossroads of Precision Medicine and Treatment Decision Making in Breast Cancer

Steven J. Katz, MD, MPH

In an era of simultaneous increased evaluative testing in the United States and a rise in early-stage breast cancer diagnosis, it’s important that those facing treatment decisions for curable cancer understand the advances and advantages in precision medicine, explained Steven J. Katz, MD, MPH.

“The most immediate opportunity for precision medicine is to reduce the burden of treatment in a patient with a favorable cancer diagnosis,” said Katz, professor, departments of medicine and health management and policy, University of Michigan, during a presentation at the 2016 Lynn Sage Breast Cancer Symposium.

Katz provided insights gleaned from numerous cancer care studies, including preliminary data from the iCanCare Cancer Study, which included responses from a survey of 5,000 women newly diagnosed with breast cancer on issues related to evaluative testing and treatment decision making.

The current context in which breast cancer patients make treatment decisions often doesn’t support the practical applications of precision medicine, explained Katz. Most treatment decisions, he noted, are made during the first patient-physician encounter. In addition, during the first year that patients receive treatment, they often undergo multi-modal therapies by different specialists. “When a woman walks into the exam room there’s a lot on the line. It’s not surprising how fast decision making unfurls,” said Katz, who argued for more a deliberative process.

The primary goals of precision medicine should be to dial down unnecessary treatment, said Katz, such as the use of aggressive surgical options in favor of breast-conserving surgery (BCS); to omit or limit the use of radiation and chemotherapy; and to reduce the burden of hypofractionated whole breast irradiation (HF-WBI).

The analytical and clinical validity of tumor biology testing has changed radically over the last 15 years, explained Katz, conferring real benefits in precision medicine as it relates to systemic chemotherapy, including reducing overtreatment, improving quality of life, and reducing disparities among cancer populations. As a result, said Katz, the uncertainty in the exam room with regard to chemotherapy recommendation is incredibly low. In a subpopulation of ER-positive, HER2-negative iCanCare patients (n = 1527), Katz noted that only 14% of clinicians did not offer a recommendation for or against chemotherapy, instead leaving it up to the patient, 22% of whom initiated treatment.

When it comes to precision medicine and locoregional treatment, that same high level of confidence doesn’t hold true for surgical recommendations, said Katz. In initial surgery recommendations, 31% of patients weren’t provided a recommendation for lumpectomy or mastectomy by their surgeon. “There’s a lot more dangling uncertainty in the surgical exam room,” said Katz.

Confusing both the surgeon and the patient, posited Katz, is the rapid rise in cancer genetic testing, which offers both promises and challenges to promoting less-invasive locoregional over more aggressive or systemic treatments. “We’re just at the beginning of understanding genetic multi-panel testing in treatment decision making,” said Katz.

Nearly 40% of women (n = 2409) at an average risk of breast cancer, and more than 60% of those with either intermediate or high risk, said they wanted genetic testing, according to preliminary data from the iCanCare Study, noted Katz. Further complicating the application of genetic testing is the timing of the test, the role of the clinician who ordered the test, and whether or not the patient received genetic counseling.

When it comes to contralateral prophylactic mastectomy (CPM) where the non-affected breast is also removed, confusion is particularly evident with serious consequences for overtreatment, said Katz. Among women with abnormal genetic test results (n = 375), more than 60% of surgeons said they would not offer BCS toBRCAcarriers. Despite that, Katz said he is seeing a concerted effort within the surgical community to advocate against the push for aggressive treatment. Of women who said their surgeon recommended against CPM (n = 859), slightly more than 2% ultimately chose CPM.  

Despite this increasingly complex era of decision making, Katz concluded there’s a “cultural sea change” in oncology focused onprimum non nocere, first do no harm, with treatment options increasingly in favor of reducing the burden of treatment instead of employing any and all measures to “rescue the incurable.” To this end, Katz is part of the multidisciplinary Cancer Surveillance and Outcomes Research Team (CanSORT), which is building a decision tool to help women with breast cancer fully understand their treatment options and the risks involved.

Katz said he hopes that insights in breast cancer will improve decision making for the larger cancer care community. “Breast cancer is the paradigm for how precision medicine will improve cancer care treatment.”

Reference:

Katz S. Precision Medicine and Treatment Decision Making: Insights from Encounters with Breast Cancer; September 22-25, 2016; Chicago, IL.