Secondary chemoprevention using short period (3 months) of LHRHa as an option for men with low-risk localized prostate cancer (LRPC) before active surveillance (AS).

Abstract

e15105 Background: Definition of LRPC and candidates for AS remains problematic. Relevant markers that reflect tumor aggressiveness are still to be determined. When AS is used it can be difficult to assess disease progression despite surveillance with PSA and repeat biopsies. Moreover, 20-50% of patients on AS were over the windows of curability when radical treatment was triggered. The current knowledge of PC suggests that aggressiveness should be assessed not only in terms of clinical features but also in terms of response to Androgen Deprivation Therapy (ADT). Methods: 83 men with LRPC (T1c or T2a PC; PSA ≤10ng/ml; Gleason score ≤6) whom have chosen prostate cancer management without radical therapy were included. They then underwent AS after receiving one injection of ELIGARD-22.5. AS consisted of PSA every 3 months (mo) and biopsies (≥12 cores) every 12mo. Patients were stratified at diagnosis according to age at diagnosis, PSA, PSA density, PSA nadir, bio-testosterone, dynamic MRI staging, % positive cores and length of tumor on the diagnosis biopsy. Predictive factors of recurrent PC observed on biopsy were tested using a Cox regression and Markov models. Results: Mean age at diagnosis of LRPC was 64 years, (standard deviation, 6.2 years). Median time to follow-up after diagnosis biopsy was 31mo. Surveillance biopsies were positive for 37 men (44%) (7 with Gleason score>6). In the subgroup of insignificant PC according EPSTEIN criteria surveillance biopsies were positives for 17/48 men (35%) (2 with Gleason score>6). Expected results from literature on classical AS were 60-70% of positive biopsy and 10-21% of upgraded biopsy at the first repeat biopsy. Predictive factors of prostate cancer observed on biopsy were: PSA nadir at 3mo <0,1ng/ml (OR=1.8; 95%CI 1.0 to 3.3 p=0.04), positive core biopsy>1(OR=1.7; 95%CI 1.0 to 2.9; p=0,03), and >T1c detectable tumor on MRI (OR=2.9; 95%CI 1.4 to 5.9; p=0.003). Conclusions: Results obtained with 3mo of LHRHa for LRPC suggest that ADT response can be used firstly to reduce prevalence of primary PC lesions and secondly in order to identify PC able to castration resistance and consequently which require radical treatment.