Dynamics in the Prostate Immune Microenvironment Induced by Androgen Deprivation Therapy

Background The influence of testosterone on the prostate's immune microenvironment remains unclear. This study aims to elucidate the dynamics of immune cells in the prostate following androgen deprivation therapy (ADT). Methods We retrospectively compared prostate needle biopsy and radical prostatectomy specimens from 33 patients who underwent both procedures, along with neoadjuvant ADT at a single institution. Immune cell infiltration in the cancer and stroma areas was assessed using multiplex fluorescence immunohistochemistry. Results Post-ADT, all immune cells, including CD4(+) T cells, CD8(+) T cells, Foxp3(+) regulatory T cells, CD204(+) macrophages, and CD20(+) B cells, significantly increased in the prostatectomy specimen. However, few immune cells were detected in the biopsy of the same patients (p < 0.001). The number of CD20(+) B cells in the cancer area was significantly lower post-ADT in high-risk cases according to the NCCN classification (p = 0.020). This difference was significantly associated with the Gleason Grade Group, rather than PSA levels or T classification (p < 0.001). However, no significant difference was observed in the recurrence rate between Grade Groups 1, 2, 3 and 4, 5 (p = 0.991). There was no significant difference in immune cells other than CD20(+) B cells when divided into NCCN classifications. Conclusions The marked increase in immune cells following ADT suggests an intensified immune response against prostate cancer.