CT-Based Quantification of Prostate Volume Change After LHRH-Agonist Androgen Deprivation: A Prospective,...

Area of Science:

• Oncology
• Radiation Oncology
• Urology

Background:

• Androgen deprivation therapy (ADT) is standard for high-risk prostate cancer, often combined with radiotherapy (RT).
• Prostate shrinkage from ADT can improve RT planning, but data on short-term, patient-level volume changes are limited.

Purpose of the Study:

• To prospectively evaluate prostate volume changes in patients receiving short-course luteinizing hormone-releasing hormone agonist (LHRHa) therapy.
• To assess the proportion of patients achieving clinically significant prostate shrinkage (≥15%) within 8 weeks.
• To explore correlations between volume changes, PSA, and testosterone levels.

Main Methods:

• Prospective study of 47 patients receiving 6-month depot LHRHa (leuprolide).
• Independent contouring of prostate volumes by three radiation oncologists on CT scans at baseline and ~8 weeks.
• Measurement of PSA and testosterone levels; statistical analysis of volume change, PSA, and testosterone correlations.

Main Results:

• Mean relative prostate volume reduction ranged from -18.5% to -21.3% across observers.
• Over 60% of patients achieved ≥15% prostate shrinkage within 8 weeks.
• Significant decreases in PSA and testosterone were observed; moderate correlations found between PSA and testosterone levels.

Conclusions:

• Short-course LHRHa therapy effectively induces CT-measured prostate cytoreduction (≥15% shrinkage) in over half of patients within 8 weeks.
• Prostate downsizing is reproducible and accompanied by significant PSA/testosterone declines, but biochemical response doesn't predict volumetric change.
• Findings support a neoadjuvant 'window' of LHRHa before RT simulation; further studies needed to refine predictors and compare ADT agents.