PREVALENT DECREASE OF THE EGF CONTENT IN THE PERIURETHRAL ZONE OF BPHTISSUE INDUCED BY TREATMENT WITH FINASTERIDE OR FLUTAMIDE

The aim of the present investigation is to verify whether treatment wi th Finasteride or Flutamide influences the regional distribution of te stosterone (T), dihydrotestosterone (DHT), and epidermal growth factor (EGF) in benign prostatic hyperplasia (BPH) tissue. Thirty seven BPH patients were studied: 15 untreated, 9 treated with Flutamide (750 mg/ day for 2 months), and 13 treated with Finasteride (5 mg/day for 3 mon ths). Testosterone and DHT were evaluated by radioimmunoassay (RIA) af ter purification of the extracts on celite columns, and EGF was evalua ted by RIA after purification on Sep-pak C18 cartridges in total tissu e and in periurethral, subcapsular, and intermediate zone. In the untr eated group, T, DHT, and EGF of the periurethral region are higher tha n those of the subcapsular zone (P < 0.01 for T and P < 0.001 for DHT and EGF). In the Flutamide group, DHT is not modified, T is increased (P = 0.045), and EGF is decreased in total tissue (P < 0.02) and in th e periurethral zone (P < 0.01). In the Finasteride group, T is increas ed (P < 0.001), and DHT and EGF are decreased (P < 0.001), particularl y in the periurethral zone. A positive linear correlation between DHT and EGF is observed in the Finasteride and in the untreated groups. In conclusion, in BPH the production of EGF is a DHT-dependent receptor- mediated function. The reduction of this growth factor during both tre atments, associated with a fall of DHT in only the Finasteride group, is particularly evident in the periurethral zone. Since Finasteride re duces prostatic volume, mainly of the periurethral zone, we can specul ate that DHT is responsible, either directly or indirectly through gro wth factors such as EGF for the enlargement of this region and thus re sponsible for urinary obstruction.