Low PSA metastatic androgen-independent prostate cancer

Objectives: To describe the clinical parameters of low PSA, progressive met astatic androgen-independent prostate cancer. Methods: From April 1995 to May 1999, we selected 18 patients with clinical ly progressive androgen-independent prostate cancer and low PSA (less than or equal to 10 ng/ml). Patients received cisplatin based therapy. Specimens from the primary tumor were reviewed and neuroendocrine differentiation wa s determined with chromogranin-A and neuron-specific enolase immunocytochem ical staining. Results: The median initial PSA level was 1.6 ng/ml (0-9.5). Each patient d emonstrated elevation of at least one of the following markers: carcinoembr yonic antigen, CA 19-9, CA 15-3 a nd CA 125 CA. Metastases involved bone in 11 patients (61.1%) - 5 (27.7%) blastic, 2 (11.1%) lytic, and 4 (22.2%) co mbined - liver in 10 patients (55.5%), lymph nodes in 8 (44.4%), and lung i n 6 (33.3%); solitary sites as orbit, skin and spleen were noted as well. A prostatic pelvic mass was detected in 13 patients (72.2%). Of the 12 patie nts who consented to chemotherapy, 8 (66.6%) achieved an objective response (95% Cl, 34.8-90%), including 1 patient with complete response. Hematoxyli n and eosin evaluation revealed two major groups: neuroendocrine tumors, ei ther pure small cell cancer in 6 patients (37.5%) or combined small cell ca ncer and adenocarcinoma in 8 (50%), and predominant poorly differentiated p rostate cancer in 2 (12.5%). Neuroendocrine immunoreactivity was detected i n all the specimens. Conclusions: Progressive androgen-independent prostate cancer with low seru m PSA is characterized by visceral metastases, high proportion of lytic bon e disease, sensitivity to cisplatin-based chemotherapy, and histological fe atures of small cell or poorly differentiated prostate cancer. In this subg roup of patients, selection of the therapeutic approach can be based on cli nical parameters. The rise of the serum markers may aid in the diagnosis an d follow-up of these patients. Copyright (C) 2000 S. Karger AG. Basel.