Long‐term follow‐up after radiotherapy for prostate cancer with and without rectal hydrogel spacer: a pooled prospective evaluation of bowel‐associated quality of life

Objective To evaluate the long‐term bowel‐associated quality of life (QOL) in men after radiotherapy (RT) for prostate cancer with and without the use of rectal hydrogel spacer. Patients and Methods The patients’ QOL was examined using the Expanded Prostate Cancer Index Composite (EPIC) and mean changes from baseline in EPIC domains were evaluated. A total of 215 patients from a randomised multi‐institutional trial of RT, with or without hydrogel spacer, with a QOL endpoint were pooled with 165 non‐randomised patients from a single institution with prospective QOL collection in patients with or without hydrogel spacer. The proportions of men with minimally important differences (MIDs) relative to pre‐treatment baseline in the bowel domain were tested using repeated measure logistic models with a pre‐specified threshold for clinically significant declines (≥5 equivalent to MIDx1 and ≥10 equivalent to MIDx2). Results A total of 380 men were evaluated (64% with spacer and 36% without) with QOL data being available for 199 men with >24 months of follow‐up [median (range) 39.5 (31–71.4) months]. Treatment with spacer was associated with less decline in average long‐term bowel QOL (89.4 for control and 94.7 for spacer) with differences at >24 months meeting the threshold of a MID difference between cohorts (bowel score difference from baseline: control = −5.1, spacer = 0.3, difference = −5.4; P