Feasibility intervention to increase exercise outcome expectations among breast cancer survivors.

e21584 Background: Exercise is associated with decreased mortality and recurrence risk and improved quality of life for breast cancer survivors (BCS). Roughly 1/3 of BCS exercise enough to experience these benefits. A promising strategy to increase exercise among BCS is to target outcome expectations (OEs), or what one expects to obtain or avoid from a behavior. OE dimensions include 1) importance – value placed on the outcome(s); 2) certainty - perceived probability outcome(s) will occur; and 3) accessibility – the frequency with which outcome(s) are considered. Methods: This RCT tested the feasbility and effects of a self-directed booklet designed to increase OEs and exercise. It was created in collaboration with BCS who successfully use exercise to manage long term side effects. OEs were measured through online surveys and exercise was measure with a Fitbit accelerometer. Data was collected at baseline, 4, 8 and 12 weeks post intervention. Feasibility was defined as the extent to which participants made use of intervention materials and was assessed through 9 researcher related questions. Results: The sample is mean age of 58, 74% white, 26% black, an average 2.5 years post treatment and about 1/3 take an AI or SERM. The booklet “somewhat” (mean = 3.24, SD = 1.8 on 1-5 Likert scale) made use of the booklet, as intended. OEs increased 0.01 points over time in the intervention arm, compared to the control arm ( p = 0.3555); 0.4 points more for black participants compared to white ( p = 0.0003); 0.2 points per every unit of increased exercise self-efficacy ( p < 0.0001), and 0.01 points per month participants were closer to their time of cancer surgery ( p = 0.0037). Intervention arm participants increased their weekly steps by 970, every 4 weeks, compared to participants in the control arm ( p = 0.0283). Conclusions: Overall the intervention was well received by participants, had positive effects on OEs and exercise and can easily be translated into practice with need for minimal resources. Significant differences were noted for black compared to white participants, thus it is necessary to understand racial differences in exercise beliefs when designing future exercise interventions. Clinical trial information: NCT02348710.