Rectal and urinary dysfunction in the TROG 03.04 RADAR trial for locally advanced prostate cancer

Background: The RADAR trial determines whether adjuvant androgen suppression, bisphosphonates and radiation dose escalation for localised prostate cancer (PC) may improve oncologic outcomes. This study examines whether these measures increase rectal and urinary dysfunction and are secondary trial endpoints.

Methods: Using a 2×2 factorial trial design men with locally advanced PC were randomly allocated 6 months i.m. leuprorelin prior to radiotherapy either alone or followed by 12 months i.m. leuprorelin. These two groups received 18 months i.v. zoledronic acid (Z) commencing at randomisation or no further treatment. Radiotherapy dose was escalated in a regulated way using external beam techniques (EBRT) or by a high dose rate brachytherapy (HDRB) boost. Prevalence rates of rectal and urinary dysfunctional symptoms were compared at baseline, the end of RT, 18 and 36 months according to treatment arm, dose and technique using multiple regression models.

Results: Between 2003 and 2007, 1071 men were randomly allocated and eligible for inclusion in this study. No persistent differences in rectal or urinary dysfunction were attributable to treatment arm or to increasing EBRT dose. However following HDRB statistical increases (p<0.001) in urinary dysfunction were measured using the EORTC PR25 instrument at 18 and 36 months.

Conclusion: Adjuvant androgen suppression, bisphosphonates and increasing EBRT dose did not increase rectal or urinary dysfunction in this trial. However dose escalation using HDRB increased urinary dysfunction.