Bicalutamide (150 mg) monotherapy versus LHRHa as neoadjuvant treatment in intermediate- and high-risk prostate cancer: A case matched study.
226 Background: The role of neo-adjuvant Lutenising Hormone Releasing Hormone Agonist (LHRHa) therapy prior to radical radiotherapy of intermediate and high risk prostate cancer (PC) has been clearly defined. Anti-androgen (AA) monotherapy is often used as an alternative to castration therapy in this setting due to a more favorable toxicity profile, however the evidence base is weaker. We compared biochemical failure free survival (BFFS) and prostate-specific antigen (PSA) kinetics in men receiving radical radiotherapy for localised prostate cancer and neo-adjuvant hormones with either AA or LHRHa therapy. Methods: All men with intermediate and high risk PC treated with AA monotherapy prior to radical prostate radiotherapy between April 2004 and December 2008 were individually case matched for key prognostic factors with men treated with neoadjuvant LHRHa monotherapy at our institution. BFFS, PSA kinetics, and absolute pre-RT, post neo-adjuvant hormone PSA (PRPH-PSA) level were analyzed. Results: Sixty five men treated with AA monotherapy were matched to with 65 men treated with LHRHa. The median follow-up was 74 months and 67 months, respectively. Phoenix BFFS was seen in 14 (23.4%) and nine (13.8%) of AA and LHRHa patients respectively with the log rank test indicating no statistically significant difference between the groups. Statistically significant differences were seen between groups in the PRPH-PSA with a geometric mean of 2.0ng/ml (range 0.1 – 11.2) for AA patients and 1.0ng/ml (range 0.1 – 11.1) for LHRHa patients (p<0.001). There was no significant difference between groups in the geometric mean PSA halving time or velocity during the neo-adjuvant period. A PRPH-PSA of less than 1.0ng/ml and less than 0.1ng/ml was seen in 16 (24.6%) and two (3%) of the AA patients and 34 (52.3%) and three (4.6%) of LHRHa patients, respectively. Conclusions: Our case matched study demonstrates that there was no statistical difference in BFFS between patients receiving neo-adjuvant AA versus LHRHa at median follow-up of 72 months. AA monotherapy resulted in less PRPH-PSA suppression when compared to neo-adjuvant LHRHa alone. Longer follow-up is required to determine if the differences in PSA kinetics translate into clinically meaningful differences.