THE ROLE OF SOMATOSTATIN ANALOGS IN COMPLETE ANTIANDROGEN TREATMENT IN PATIENTS WITH PROSTATIC-CARCINOMA

Somatostatin analogues (SMS-A) have been found to inhibit the growth o f experimental tumors, as of prostate cancer, via several mechanisms a s antihormonal and direct antimitogenic actions. It was demonstrated a lso that several SMS-A induce greater prostatic tumor regression with more pronounced histological changes if combined with LHRH analogues o r in association with complete androgen blockade (CAB). In a phase II clinical trial we administered, in addition to CAB, SMS-A octreotide i n 14 patients with stage D2 (group B) prostate cancer-8 previously hor monally treated (PHT) and 6 without any previous hormone treatment (NP HT); 4 other patients, 3 NPHT and one PHT, were treated with CAB only (group A). Antiandrogen and antitumoral activity followed assaying a) plasma testosterone b) prostatic specific antigen (PSA) c) prostatic a cid phosphatase (PAP) levels and d) objective to) and subjective (s) c linical improvement according to WHO criteria. Somatostatin activity w as evaluated assaying Insulin like Growth Factor-1 (IGF-1) and Epiderm al Growth Factor (EGF), In group B we observed 3 responses, with the b est quality of response (oPR/sCR) among the 6 NPHT-patients (50%) and 3 responses among the PHT-patients (37,5%), two of them with an incomp lete PHT. In group A, 2 out of 3 NPHT-patients had a response (oPR/sPR ). Among group B patients we observed long symptom-free survival, when they responded (17 months), in comparison to group A patients (12 mon ths), but almost the same total duration of survival in the two groups , 18.5 and 18 months, respectively. EGF and IGF-1 serum levels showed a distinct drop parallel to the decrease of PSA serum levels, among th e patients with response vs. nonrespondent patients of group B during the treatment, Although our results showed that octreotide in small do ses, in addition to CAB, having mild toxicity, enhance number, quality and perhaps the duration of symptom-free responses in patients with s tage 2 prostate cancer, the therapeutic efficacy of this combined trea tment remains to be ascertained in wider and better randomized clinica l trials.