Risk Perceptions In Localized Breast Cancer (Bc)

9534 Background: Risk perceptions (RP) play an important role in decision making in localized BC. Little is known about RP in the context of adjuvant (adj) therapy decisions. We examined the accuracy of estimate of absolute benefit of adj therapy among patients (pts) with localized BC and sought to identify determinants of accurate RP. Methods: A cross-sectional survey was conducted in localized (Stage I-III) BC pts within 3 months after surgery at 4 U.S. cancer centers. Pts completed the Decision Quality Instrument, which includes items on BC knowledge, numerical estimates of benefit of adj therapy, and communication with providers. We analyzed pts with Stage I/II and calculated objective estimates of benefit of adj therapy using Adjuvant! Online. Based on published data, an estimate that was +/- 5% of the calculated risk was considered correct. We used multivariable (MV) regression to identify determinants of accuracy including tumor stage, age, adj treatment, education, total knowledge score, and decision involvement. Results: 192/249 (77.1%) pts completed the survey; analyses were limited to 166 pts stage I/II with complete risk estimate data. Mean age was 56.4 years (SD 12.1), 83% of respondents were white, and 58.5% were college graduates. 56.3% had stage I and 43.7% had stage II disease. Most (95.6%) had some type of adj therapy, either endocrine therapy only (43.2%), chemotherapy only (15.3%), or both (32%). On average, pts estimated the absolute benefit of adj therapy to be 31.8% (SD24.9), and this varied by stage (28.4 and 35.9 for stage I and II, p=0.06). The overall estimate for this sample from Adjuvant! Online was 11.8% (SD 7.67) and this varied by stage (8.6/16.0 for stage I/II respectively, p<0.001). Few pts (18.1%) had accurate estimates and the majority (68.3%) overestimated the benefit. In MV logistic regression analysis, only BC knowledge score was associated with accurate estimate of benefit (OR 1.36 95%CI 1.04, 1.8). No other factors were significantly associated with accuracy. Conclusions: Pts with localized BC overestimated the absolute benefit of adj therapy by an average of 20 percentage points. Some pts may be taking on risks of adj therapy without accurate knowledge of the benefits, calling into question whether these decisions are truly informed.