Prehabilitation to Improve Positioning Reproducibility in Patients Undergoing Pelvic Radiation Therapy

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Reproducible patient positioning is essential for precision in radiation therapy (RT) delivery. However, a retrospective review of pre-treatment imaging demonstrated variability in daily patient set-up. We tested the hypothesis that a structured daily pre-treatment stretching regimen is both feasible and effective for minimizing variability in positioning, as measured by sacral slope angles (SSA). After obtaining IRB approval, we had 8 female patients undergoing pelvic radiotherapy perform a structured daily hip exercise regimen (extension and external rotation) immediately prior to both simulation and daily treatment, throughout the RT course. The control group of 20 patients (17 female and 3 male) had usual care. SSA measurements on daily pre-treatment imaging were compared to SSA measurements from the simulation CT for 5 weeks. The extent of SSA variability between two groups and over time was analyzed using a linear mixed model. The same two readers independently measured SSA of all subjects, comparing SSA on the day of simulation to SSA measured on each day of RT. The average variation in SSA among the intervention subjects was 0.913° (±0.582°), with a range among subjects of 0.57°-1.3°. The average variation for the control subjects was 2.27° (±1.43°), with range among subjects of 1.22° - 5.09°. The difference between the two groups was statistically significant (p=0.002). There was a statistically significant SSA variation between groups at each week of treatment (Week (wk) 1: p = 0.007, wk 2: p = 0.008, wk 3: p = 0.01, wk 4: p = 0.005, wk 5: p = 0.008). There was no significant variation among the intervention subjects between week 1 and later weeks (wk 2: p = 0.88, wk 3: p = 0.74, wk 4: p = 0.97, wk 5: p = 0.40), whereas subjects in the control group demonstrated significant SSA variation between week 1 and the fourth week of therapy (wk 2: p = 0.87, wk 3: p = 0.92, wk 4: p = 0.02, wk 5: p = 0.22). There were no reported adverse effects of the stretching regimen. We demonstrated a significant decrease in the variability of SSA by implementing a simple pre-treatment stretching program, whereas control subjects exhibited an increasing variability of SSA over the course of treatment. We conclude that there is a potential benefit for prehabilitation during pelvic RT. A larger clinical trial is required to determine whether a pre-treatment stretching program would result in clinical benefit.