This study aimed to examine how biomarker information would impact patients' preferences and physicians' recommendations for adjuvant breast cancer therapy.At the 18-month follow-up, participants in a large, double-blind randomized controlled trial of adjuvant chemotherapy with bevacizumab or placebo (E5103) were surveyed about their preferred treatment (either chemotherapy A alone or chemotherapy A+B) in two hypothetical scenarios: (1) without biomarker information; and (2) after learning that they tested positive for a "B-receptor" which modestly increased both the benefit and toxicity expected with chemotherapy A+B. We performed a cross-sectional analysis of the prospectively collected survey data and used the McNemar's test to examine changes in treatment preferences. A one-time survey of clinical investigators who enrolled patients on the trial evaluated physician recommendations in response to the same biomarker information.439 patients completed both scenarios on 18-month survey. Most participants preferred A+B in both scenario 1 and 2 (77 and 76% respectively). The increase in benefit and toxicity associated with the positive biomarker information in scenario 2 led 60/439 (14%) of patients to switch their treatment preference. The corresponding physician survey revealed that most physicians chose regimen A+B in scenario 1 (77%), and moreso after the biomarker information was available in scenario 2 (84%).Information about a positive biomarker indicating increased benefit and toxicity from additional chemotherapy did not change many participants' preferred treatment. The majority preferred the most effective course in both scenarios. Similarly, most investigators discounted increased toxicity and valued increased benefit. Parent Trial Registration: NCT00433511.
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