Pelvic prehabilitation: pelvic exercises assist in minimizing inter-fraction sacral slope variability during radiation therapy

Abstract

Introduction: Prehabilitation for radiation therapy is not well studied. Retrospective data shows variability in set-up positioning of patients during daily pelvic RT. We hypothesize that a brief structured daily exercise regimen is feasible for subjects to perform before RT and may minimize variability in positioning as measured by sacral slope angles (SSA) on lateral views. Determining feasibility and effectiveness of these exercises in decreasing set-up variability has clinical implications, both for targeting treatment sites and preventing adverse effects. Methods: Subjects in the exercise intervention condition (n=8, 8 F) performed a structured daily hip exercise regimen throughout the duration of RT, and subjects in the historical control condition (n=20, 17 F, 3 M) had usual care. For each patient, SSA measurements were compared to SSA measurements from the simulation CT for 5 weeks during RT. The extent of variability of measurements between two conditions was studied using a linear mixed model. For all patients in both conditions, the same two readers independently measured SSA to compare angles on day of simulation against the angles measured from each day of RT. Results: The average variation in SSA for intervention condition was 0.913° (±0.582°), with range among patients 0.57°-1.3°. The average variation for control condition was 2.27° (±1.43°), with range among patients 1.22° - 5.09°. The difference between two conditions was statistically significant (p=0.0019). Comparison of SSA variation between conditions demonstrated a statistically significant difference at each week (wk 1: p = 0.0071, wk 2: p = 0.0077, wk 3: p = 0.011, wk 4: p = 0.005, wk 5: p = 0.0079). The exercise intervention condition had no significant variation between week 1 and later weeks (wk 2: p = 0.876, wk 3: p = 0.741, wk 4: p = 0.971, wk 5: p = 0.397). The control condition showed greater SSA variation between week 1 and later weeks (wk 2: p = 0.868, wk 3: p = 0.915, wk 4: p = 0.015, wk 5: p = 0.224), with significant variation between weeks 1 and 4. No subject reported any adverse effects. Conclusion: We observed a significant decrease in sacral slope variability in our exercise cohort as compared to historical controls. SSA variation for control condition increased over the course of treatment with significant difference noted between week 1 and 4. A larger clinical trial is required to evaluate the potential clinical benefits of a structured daily exercise regimen during pelvic RT. References: Silver JK, Baima J. Cancer prehabilitation: an opportunity to decrease treatment-related morbidity, increase cancer treatment options, and improve physical and psychological health outcomes. American journal of physical medicine & rehabilitation. 2013 Aug 1;92(8):715-27. Lukez A, O’Loughlin L, Bodla M, Baima J, Moni J. Positioning of port films for radiation: variability is present. Medical Oncology. 2018 May 1;35(5):77. Kwon JW, Huh SJ, Yoon YC, Choi SH, Jung JY, Oh D, Choe BK. Pelvic bone complications after radiation therapy of uterine cervical cancer: evaluation with MRI. American Journal of Roentgenology. 2008 Oct;191(4):987-94. Stubblefield MD. Radiation fibrosis syndrome: neuromuscular and musculoskeletal complications in cancer survivors. PM&R. 2011 Nov 1;3(11):1041-54.