Shared decision-making in breast cancer: discrepancy between the treatment efficacy required by patients and by physicians.

Several factors can influence individual perceptions of the expected benefit of recommended adjuvant treatment for breast cancer. This study investigated differences between patients and physicians with regard to the required efficacy of treatment and the factors influencing patients' and physicians' willingness to accept different therapeutic options. A total of 9,000 questionnaires were distributed to patients with breast cancer, and 6,938 questionnaires were distributed to physicians treating breast cancer patients. The patients were asked for personal information and about their medical history and experiences during treatment. The physicians were asked about personal information and their specialty and work environment. The treatment efficacy required by the two groups was assessed using six virtual cases of breast cancer and the treatment regimens proposed, with specific benefits and side effects. A total of 2,155 patients and 527 physicians responded to the questionnaire (return rates of 23.9 and 7.6 %). Significantly different ratings between patients and physicians with regard to the expected benefit of certain treatment options were observed. The differences were noted not only for chemotherapy but also for antihormonal and antibody treatments. Whereas physicians had a quite realistic view of the expected treatment benefits, the patients' expectations were varied. Approximately one-fifth of the patients were willing to accept treatment regimens even with marginal anticipated benefits, whereas one-third required unrealistic treatment benefits. Several influencing factors that were significantly associated with the quality rating of treatment regimens in the groups of breast cancer patients and physicians were also identified. In contrast to physicians, many breast cancer patients required treatment benefits beyond what was realistically possible, although a large group of patients were also satisfied with minimal benefits. Individual factors were also identified in both groups that significantly influence thresholds for accepting adjuvant treatment, independently of risk estimates and therapy guidelines.