Effect on prostate volume following neoadjuvant treatment with an androgen receptor inhibitor monotherapy versus castration plus an androgen receptor inhibitor in prostate cancer patients intended for curative radiation therapy: A randomised study.

To avoid pubic arch interference, prostate cancer patients are treated with neoadjuvant androgen deprivation therapy (ADT) to achieve prostate volume (PV) reduction prior to radiation treatment. The aim of the present randomised study was to compare the effects on PV of two regimens of ADT, an androgen receptor inhibitor monotherapy vs. castration plus an androgen receptor inhibitor. Consecutive patients with non-metastatic prostate cancer were included in a randomised neoadjuvant study, comparing an androgen receptor inhibitor monotherapy vs. castration plus an androgen receptor inhibitor. PV was assessed prior to the start of endocrine neoadjuvant treatment and prior to the start of radiation therapy (RT). PV assessment was performed by transrectal ultrasound. A total of 110 patients were included. Final sample constituted 88 (80%) patients due to lack of PV information. Castration plus an androgen receptor inhibitor was more effective in PV reduction compared with an androgen receptor inhibitor alone (P<0.001). Planning target volume decreased in the combination arm. There was no significant difference in clinical or demographic or length of neoadjuvant hormonal treatment between the groups. Overall, a significantly larger PV reduction was achieved by castration plus androgen receptor inhibitor, as compared with androgen receptor inhibitor monotherapy. The PV reduction, however, appeared not to translate into better health associated quality of life during the subsequently given curative intended combined EBRT and HDR-brachytherapy. Potential differences between these two treatments regarding anti-tumor effects on micro metastatic disease and radiation potentiating effect remains to be addressed in future prospective trials.