Precision Medicine Increasingly Guides Decision-Making for Patients with Breast Cancer

Breast cancer serves as a model for using precision medicine to guide treatment decisions and improve patients’ quality of life, according to a presentation at the 2016 Lynn Sage Breast Cancer Symposium.
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According to Steven Katz, MD, Director of Sociobehavioral Research Program, University of Michigan Comprehensive Cancer Center, breast cancer is the ideal model for how precision medicine will improve cancer care, because precision medicine techniques are more advanced in breast cancer than in other forms of cancer. Quality of life plays a major role in patients’ decision making due to advanced treatment techniques, genetic testing, and good prognoses for most newly diagnosed patients. Approximately 30% of patients with breast cancer underwent genetic testing in 2015, more than double the percentage 3 years prior.

In his presentation, Dr Katz cited data from a study published in Cancer that surveyed 2880 patients treated for early-stage breast cancer in 2013 and 2014. Patients’ clinical information was correlated with their genomic testing results and coupled with questionnaires completed by their surgeons and oncologists. Surveyors were interested in the rate at which patients decided their courses of treatment after initial diagnosis as well as the confidence levels of oncologists in recommending based on the results of genetic tests.

Results of the study showed that after initial diagnosis, many patients made treatment decisions quickly and opted to receive treatment from the first clinician they consulted. Among the 1527 patients with estrogen receptor-, progesterone receptor-positive, HER2-negative invasive cancer, 72% decided on chemotherapy if their oncologist recommended it. Approximately 20% of patients chose chemotherapy on their own if their oncologist did not recommend it. Only 14% of the oncologists did not offer an opinion to their patients one way or another, signifying a high level of certainty about chemotherapy among oncologists.

Dr Katz referenced how oncologists are increasingly reliant upon the results of genetic assays in developing their recommendations. When patients tested at a high risk on a 21-gene assay, almost every oncologist recommended chemotherapy as first-line treatment. Oncologists even increased their recommendations in favor of chemotherapy for all patients who tested high risk on a gene assay, regardless of their node status.

As oncologists increasingly order genetic tests before surgery and become more confident about discussing the implications of test results, Dr Katz envisions breast cancer precision medicine as a continuing “paradigm for how precision medicine will improve cancer care.”