Is there a relationship between testosterone levels at the end of short-term androgen deprivation therapy and outcomes in intermediate risk prostate cancer? Prospective data from a phase III trial.

Abstract

78 Background: The purpose of this analysis was to assess whether the testosterone level measured at the end of short term androgen deprivation therapy (STADT) and prostate radiotherapy (RT) has an impact on treatment outcomes in patients with intermediate risk prostate cancer (IRPC) treated on a randomized trial (PCS III ClinicalTrials.gov #NCT00223145). Methods: From December 2000 to September 2010, 400 patients with IRPC received 6 months of STADT (bicalutamide 50mg die and goserelin 10.8mg x 2) and RT. Castrate level of testosterone was defined as <1.7 nmol/L: lower level <0.7 and upper level 0.7-1.7. In 347/400 patients, testosterone levels were available at the end of STADT and were divided into 3 groups based on measured testosterone levels: <0.7, 0.7 to 1.7 and >1.7 nmol/L. Patient’s characteristics were compared with ANOVA and Fisher’s exact test. Biochemical failure, prostate cancer recurrence and death were compared with Cox regression. Results: Patient’s characteristics were well balanced between the 3 groups with no statistical difference for age, performance status, PSA at start, Gleason score and stage. At the end of STADT 55.3% (192/347) presented testosterone levels <0.7 and 38.9% (135/347) levels between 0.7 and 1.7 for a total of 94.2% (327/ 347) reaching castrate levels ≤1.7 nmol/L. In 5.8% of patients (20/347) a castrate testosterone level was not achieved. With a median follow-up of 8.1 years, outcomes are shown in the table. Conclusions: In IRPC patients treated with STADT and RT, the majority of patients (94.2%) achieve a castrate level of testosterone (<1.7 nmol/L). Although we could not show a difference in outcomes between castrate and non-castrate patients, these data have to be viewed with caution given the small number of non-castrate patients studied. Source of Funding: AstraZeneca Pharmaceuticals Grant. Clinical trial information: NCT00223145. [Table: see text]