Fate of Seminal Vesicles and Prostate After Medical Castration: How Long Is the Optimal Duration of Neoadjuvant Treatment for Prostate Cancer Before Radiation?

Is prospective MRI mapping of the changes in the volume of the prostate gland in prostate cancer patients undergoing 6 months of neo-adjuvant androgen deprivation therapy a step towards a trial to determine those who may benefit from treatment intensification or extended duration?

INTRODUCTION

Neo-adjuvant androgen deprivation therapy prior to radiotherapy (RT) causes shrinkage of the prostate gland, but the changes in volume have never been mapped over time in detail, nor have the associations between volume reduction and testosterone escape or prostate-specific antigen (PSA) kinetics been determined.

METHODS

Fifty consecutive patients with prostate cancer were treated with 6 months of triptorelin prior to definitive RT. The volume of the prostate gland was measured at the outset and every 6-7 weeks thereafter using MRI scans. The volumes were calculated using a planimetric method, and inter-rater reliability was checked. Factors associated with a large initial volume and greater reductions in it were assessed.

RESULTS

The median volume at the outset was 45 cc, and the median reductions every 6 weeks thereafter were 23, 18, 9 and 5%. The inter-rater agreement was high (r > 0.9, P < 0.001). There were no baseline clinical factors associated with a high initial prostate volume, but the initial volume was associated with greater volume reduction. Testosterone escape had no effect on the reduction, and changes in volume were not reflected in PSA response kinetics.

CONCLUSIONS

Reductions in volume continue throughout a 6-month course of neo-adjuvant therapy but are greatest during the first 6 weeks. Although individualisation of the duration or intensity of the hormone treatment warrants further investigation, the role of prostate gland volume reduction remains uncertain. More detailed studies of tumour volume might be possible if the imaging required was acceptable and accessible to patients.

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.