Abstract OT3-07-03: Positive behavior change and weight loss in breast cancer survivors on hormonal adjuvant therapy: An energy balance research in cancer (EnBaR) prospective study

Abstract

Abstract BACKGROUND: Observational studies have repeatedly linked obesity to increased cancer incidence, recurrence, and mortality, leading to cancer treatment guidelines that call for maintenance of a healthy body weight, regular physical activity (PA) regardless of body mass index (BMI), and modest weight loss for overweight and obese cancer survivors (CS). Despite these recommendations, newly published reports suggest that more than 70% of CS are overweight or obese, and only 1/3 engage in the recommended levels of PA. Although trials have demonstrated that energy balance (EB) interventions are feasible in CS, it has been concluded that ongoing behavioral support is needed to implement and sustain changes in weight and PA. Through the subsequent Energy Balance Research (EnBaR) the incorporation of a weight management and PA program focused on ongoing behavioral support for breast cancer survivors (BCS) as an effective method for implementation of lifestyle modifications will be investigated. TRIAL DESIGN: This is a single-arm prospective observational study investigating if implementation of an EB Program for BCS is an effective intervention for producing lifestyle behaviors. Eligible subjects must be female BCS ≥18 years with BMI ≥25 who are initiating hormonotherapy (HT) as their only oncology treatment modality. Subjects will consult with a Registered Dietitian (RD) to establish goals based on specified interventions for reducing overall BMI at the time of initiating their prescribed HT. Subjects will subsequently receive telephone calls from the RD at bi-monthly intervals to discuss the established points of intervention, answering questions proposed by the RD from a set intervention measurement scale. Patients will also report for body composition analysis performed by the RD via InBody at Baseline, Day 90, and Day 180. InBody is a validated tool that utilizes direct segmental multi-frequency bioelectrical impedance analysis (DSM-BIA) to provide a highly accurate report of an individual's body composition. AIMS: Determine change in Percent Body Fat (PBF) and BMI during adjuvant hormone treatment for breast cancer patients. STATS/TARGET ACCRUAL: To assess % change in BMI and PBF between baseline and 180 days, one-sample t-tests will be used. Assuming an average (avg) baseline BMI of 33.7 with a standard deviation of 8.5; a sample of 120 patients will yield 89.4% power using a two-sided t-test to detect a 13% reduction in BMI to an avg of 29.32 and 82.8% power to detect a 12% reduction to an avg BMI of 29.656. Similarly, a t-test will have 83.7% power to detect a 12% decrease in % change in PBF assuming an avg baseline PBF of 41.36 with a standard deviation 10.5. The power calculations were accomplished by generating simulations of size 10,000 replications conducted at the 0.025 significance level using the TTEST procedure of SAS 9.4 [SAS Institute Inc., Cary, NC, USA]. The calculations assume a linear correlation of 0.5 between the baseline and Day 180 measurements and are Bonferroni corrected to maintain a familywise error of 0.05 for the primary analysis. All statistical analyses will be conducted using SAS 9.4. Statistical significance will be defined as p < 0.05. Citation Format: Scheuer R, Bendinger GM, Ensor Jr. JE, Nixon D, Randolph K, McGuirec E, Rados K, McNight JE, Pabbathi H, Panicker R, Johnson AT, Langlois C, Lammersfeld C, Alvarez RH. Positive behavior change and weight loss in breast cancer survivors on hormonal adjuvant therapy: An energy balance research in cancer (EnBaR) prospective study [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr OT3-07-03.