Abstract 2246: The impact of a waitlist control group on physical activity level in the activity after cancer treatment exercise oncology randomized pilot study

Abstract Background: In randomized clinical trials, control conditions such as blinding are essential for mitigating threats to validity. In exercise oncology trials, researchers are unable to blind participants to randomization, which may confer unintended consequences (i.e., crossover or dropout) that may threaten validity. Despite prior suggestions that a waitlist control is optimal for lessening these consequences, to date there is little agreement concerning control conditions in exercise oncology. Further, the use of a waitlist control is complicated by concerns regarding the ethical implications of instructing participants to delay healthy behavior change. Herein, we leveraged data from the Activity after Cancer Treatment (ACT) study to evaluate the impact of randomization to a waitlist control group on objectively assessed physical activity (PA) levels in breast cancer (BC) survivors. Methods: The ACT Study (PI: Ambrosone) was a 12-week, four-arm pilot study at Roswell Park Comprehensive Cancer Center. Participants included 37 BC survivors who were randomized to either a waitlist control group (n=10), or one of three exercise interventions of varying intensities including home-based walking (n=9), home-based Zumba (n=9), or a supervised high-intensity interval training treadmill protocol (n=9) delivered by study personnel at Roswell Park Comprehensive Cancer Center. The waitlist group was asked to maintain their usual PA during the 12-week intervention. All participants received weekly phone calls to optimize engagement and ensure Fitbit data were properly synced. For the current analysis, the primary analytic exposure was randomization assignment (control or active intervention); the analytic outcomes included steps/day, moderate-to-vigorous PA (MVPA) minutes/week and total active minutes/week as measured by the Fitbit Charge 2. ANOVA was used to assess mean group differences in steps and active minutes. Results: At study conclusion, the control group accumulated significantly fewer steps/day [6,087 (±1,353)] than the active intervention groups [8,729 (±2,585), p=0.0003]. The control group also accumulated significantly fewer MVPA minutes/week [146.2 (±114.9) vs. 264.1 (±192.3), p=0.045] and total active minutes/week [1,478 (±291.0) vs. 1,976.8 (±658.6), p=0.003] in comparison to the active intervention groups, respectively. Conclusions: BC survivors randomized to active intervention accumulated significantly more steps, MVPA and total active minutes than the waitlist group. Although the waitlist was effective for minimizing PA relative to the active arms, waitlisted participants exceeded the national step average of 4800 steps/day by 1200 steps and nearly met the minimum PA recommendation of 150 minutes of MVPA/week, potentially assuaging ethical or public health concerns regarding the delay of health-seeking behavior. Citation Format: Rikki Cannioto, Evan Davis, Karen Hulme, Chi-Chen Hong, Carol DeNysschen, Tracey O'Connor, Christine Ambrosone. The impact of a waitlist control group on physical activity level in the activity after cancer treatment exercise oncology randomized pilot study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2246.