D. Prapotnich

987 Intermittent androgen deprivation therapy: Duration of the first off treatment interval as a predictor of disease progression and prostate cancer death

INTRODUCTION AND OBJECTIVES: To analyze the association between duration of first OFF treatment interval and time to cancer specific death in prostate cancer patients who experienced biochemical recurrence (BCR) after radical prostatectomy, or radiation therapyand were treated with intermittent androgen deprivation (IAD) therapy. METHODS: We identified 158 patients who were treated with IAD therapy after BCR following prostatectomy, or external beam radiation treatment at our institution between 1992 and 2011. Ontreatment period (ONTP) consisted of three-monthly injections of gonadatropin-releasing hormone (GnRH) agonist combined with daily oral androgen receptor antagonist. Off-treatment period (OFTP) was indicated when PSA was 4 ng/ml. Criteria for resumption of hormonal therapy were PSA 20 ng/ml or clinical symptoms. Kaplan Meier curves with Uni and multivariate Cox regression model was used to identify variables associated with cancer specific survival. RESULTS: Median (Percentile 25-75) age was 65 years (6169). 110 patients were primarily treated with prostatectomy, 20 of these received salvage radiation therapy; 48 were initially treated with external beam radiation. Gleason score was 6 in 75 patients (47.4%), 7 in 61(38.6%) and 8 in 22 (13.9%) men. Median PSA at initial IAD was 9.8 ng/ml (5-20). Median duration of the first off treatment interval was 46 months (27-74) Median time from local treatment to start of IAD was 29.2 months (Range: 2-52). During a median follow-up of 7.2 years (5-10) since start of IAD, 50 patients died of disease and 18 patients died of other cause. 10-year cancer specific survival since start of IAD was 57% (95%CI: 46-66) and the corresponding overall survival was 48% (38-57) After adjusting for primary therapy, age and serum PSA at the start of IAD, presence of Gleason score 8-10, and shorter duration of the first off treatment interval after start of IAD were significantly associated with worse cancer specific survival. CONCLUSIONS: Shorter duration of first OFF treatment interval after start of IAD and higher Gleason score were significantly associated with worse cancer specific survival in prostate cancer patients who experienced BCR after radical prostatectomy or external beam radiation therapy.