Predictors for response to intermittent androgen deprivation (IAD) in prostate cancer cases with biochemical progression after surgery

ObjectiveTo define characteristics of the first cycle of intermittent androgen deprivation (IAD) that would predict for outcomes in a long term follow-up.Material and methodsIn 1996 we started a prospective study of IAD for the treatment of biochemical progression (BP) after radical prostatectomy (RP) for prostate cancer (PC). The end-points of the trial were time to clinical progression (CP) and time to castration resistance PC (CRPC). Eighty-four cases were included in the study. In all cases, after an initial induction period, an acceptable nadir to switch from on-to-off-phase of IAD was considered to be a serum PSA < 1.0 ng/ml.MeasurementsAs possible predictors for time to CP and CRPC, we analyzed pretreatment parameters such as age, Gleason Score, serum PSA, testosterone, chromogranina A (CgA) levels, and characteristics from the first cycle of IAD.ResultsMean follow-up during IAD was 88.6 ± 16.7 months; 29.7% of patients developed CRPC and 14.2% of cases showed a CP with a mean time of 88.4 ± 14.3 months and 106.5 ± 20.6 months, respectively. At univariate and multivariate analysis, the PSA nadir during the first on-phase period and the first off-phase interval resulted in significant and independent predictors (P < 0.001) of the time to CRPC and CP. In particular for cases with a PSA nadir > 0.4 ng/ml and for those with an off-phase interval ≤ 24 weeks, the risk of CRPC and CP during IAD was 2.7–2.5 and 3.0–3.1 times that for patients with a PSA nadir ≤ 0.1 ng/ml and with an off-phase interval > 48 weeks, respectively.ConclusionsCases with BP after RP selected to IAD that show at the first cycle a PSA nadir ≤ 0.1 ng/ml and a off-phase interval ≥ 48 weeks may identify candidates who will experience better response to IAD treatments and delayed CP or CRPC development.