Doctors' participation in randomized trials of adjuvant systemic therapy in breast cancer: how does it relate to their recommendations for standard therapy in breast cancer?

A cross-sectional survey of all medical and radiation oncologists in Australia was undertaken, plus surgeons listed as participants of the ANZ Breast Cancer Trials Group, to examine whether doctors' participation in randomized trials of adjuvant systemic therapy for breast cancer, is associated with their recommendations for adjuvant therapy in two clinical scenarios. Two-hundred and sixty-nine questionnaires were returned (response rate 71%). Fifty-six per cent of respondents, were participating in current adjuvant systemic therapy trials. Radiation oncologists were significantly more likely than surgeons or medical oncologists to recommend radiotherapy, while medical oncologists and surgeons were significantly more likely than radiation oncologists to recommend chemotherapy, in both clinical scenarios. In a multivariate analysis adjusting for the differences between specialist groups, respondents recommending chemotherapy were more likely to be high accruers to clinical trials (OR 3.6, 95% CI 0.93 to 13.9, P=0.08) in scenario 1, or participants of a breast cancer trials organization (OR 3.1, 95% CI 1.6 to 5.9, P=0.001) in scenario 2. Some of the variation in adjuvant systemic therapy recommendations is associated with participation in adjuvant systemic therapy trials. However, this study is unable to determine if trial participation influences opinions about adjuvant therapy, or opinions influence trial participation.