Objective: The purpose of the study was to examine the immunohistochemical stainability of prostate-specific antigen (PSA) and androgen receptor (AR) in biopsies from localised prostate cancers before treatment, after androgen deprivation and after radiation therapy.
Patients and methods: Biopsies were taken from 16 men with prostate cancer (T1-3,Nx,M0) before the start (START) of androgen deprivation with LHRH analogue, during the following pelvic lymph node dissection (PLND), and twice after radiotherapy (POSTRAD and FINAL).
Results: Malignant cells were observed in all START, PLND and POSTRAD biopsies and in 6 of 7 FINAL specimens. During androgen suppression and subsequent radiotherapy a gradual reduction in tissue immunoreactivity for PSA and AR was observed paralleled by a reduction in serum PSA. The most striking observation was the complete lack of AR stainability after combined LHRH/radiation therapy. Of the 7 patients who had a long-term follow-up after radiotherapy, 1 patient was cancer negative on biopsy and without AR and PSA stainability. Six patients with cancer-positive FINAL biopsies had regained AR stainability. Five of these latter biopsies also stained for PSA. Five of the six patients had no elevation in serum PSA.
Conclusion: After combined hormone/radiotherapy serum PSA is a relatively unreliable marker for the demonstration of residual cancer. This combination therapy leads to transient loss of immunohistochemically stained tissue PSA and AR in the residual cancer.