Intermittent Versus Continuous Androgen Deprivation Therapy for Biochemical Progression after Primary Therapy in Hormone-Sensitive Nonmetastatic Prostate Cancer: Comparative Analysis in Terms of CRPC-M0 Progression.

Introduction: To analyze whether the use of an intermittent (IAD) versus continuous (CAD) androgen deprivation therapy for the treatment of biochemical progression after primary treatments in prostate cancer can influence the development of nonmetastatic castration resistant prostate cancer (CRPC-M0). Patients: 170 male patients with an histologically confirmed diagnosis of PC, presenting a biochemical progression after primary treatments (82 after radical prostatectomy and 88 after external radiation therapy), nonmetastatic at imaging were considered for continuous (85 cases) or intermittent (85 cases) administration of androgen deprivation therapy. Methods: we retrospectively collect all data regarding histological diagnosis, primary treatment, imaging for M0-M1 staging, PSA at progression, time to biochemical progression from primary therapy, ADT used, IAD cycles, so to compare in 2 groups (IAD vs. CAD) time for progression from the beginning of ADT treatment and type of progression in terms of CRPC-M0 versus CRPC-M1 cases. Results: no significant (P= .4955) difference in the whole CRPC progression was found between IAD (25.8%) and CAD (30.5%) treatment at a mean of 32.7 +/- 7.02 months and 35.6 +/- 13.1 months respectively (P= .0738). Mean PSA at CRPC development was significantly higher in the IAD group (5.16 +/- 0.68 ng/mL) than in the CAD group (3.1 +/- 0.7 ng/mL) (P < .001). In all cases, imaging to detect M status at CRPC development was PET TC scan. At univariate analysis CAD administration significantly increases the RR for CRPC-M0 progression (RR 3.48; 95%CI 1.66-7.29; P = .01) when compared to the IAD administration, and this effect at multivariate analysis remained significant and independent to the other variables (RR 2.34, 95%CI 1.52-5.33; P = .03). Conclusions: in our population with biochemical progression after primary treatment for PC, the intermittent administration of ADT significantly reduces the risk to develop CRPC-M0 disease when compared to a continuous administration of ADT, whereas no difference between the 2 strategies in terms of CRPC-M1 progression exists.