Impact of exercise training on tumour-infiltrating T cells in human prostate cancer: A secondary analysis of a randomized controlled trial (PRO-TEST).

Exercise training reduces tumour growth by increasing tumour-infiltrating T-cell density in preclinical models. However, it remains unknown whether exercise training can modify intratumoural T cells in humans.The aim of this study was to compare the effects of an exercise training intervention versus control on human prostate intratumoural T-cell density.This study is a secondary analysis of a randomized controlled trial. We randomly allocated men (age > 18 years) with treatment-naive localized prostate cancer scheduled for radical prostatectomy 2:1 to exercise training intervention or control. The exercise intervention consisted of supervised, high-intensity interval bicycling four times per week from the time of randomization until prostatectomy. Intratumoural CD3+ and CD8+ T-cell densities in diagnostic biopsies and postsurgical prostatectomy specimens were quantified using immunohistochemistry. Between-group differences in changes from baseline to follow-up were estimated using constrained baseline linear mixed-effect models.A total of 30 participants were included (exercise intervention, n = 20; control, n = 10). We found no between-group differences in changes in CD3+ T cells [mean difference (95% confidence interval): -17 (-185; 150) cells/mm2] or CD8+ T cells [mean difference (95% confidence interval): -16 (-206; 172) cells/mm2]. Additionally, we found no statistically significant correlations between changes in T-cell density and the number of exercise training sessions attended or changes in maximal oxygen consumption.In this secondary analysis of a randomized controlled trial, we found no impact of the exercise regimen on tumour-infiltrating CD3+ and CD8+ T-cell density in human prostate cancer.