Background: Patients with prostate carcinoma generally respond to androgen withdrawal therapy, but subsequent progression to androgen-independence is frequently observed. Since androgen receptors play a key role in androgen action, the ratio of androgen receptor-containing cells in cancerous tissues was determined by immunohistochemical staining of prostate biopsy specimens for comparison with the outcome.
Methods: Sixty-two patients with untreated Stage D2 prostate carcinoma who received endocrine therapy between 1986 and 1992 were included in the present study. Biopsy tissue was stained with anti-human androgen receptor antibody, and the ratio of positively stained cells was estimated by counting 700 to 1000 cancer cells from each patient. Histologic grade, extent of bone metastases, clinical response to endocrine therapy, and outcome, were compared with androgen receptor content.
Results: Cancers with a low Gleason score had a significantly higher androgen receptor content than those with a high Gleason score. Androgen receptor content was not significantly correlated with extent of disease or tumor marker response at three months. Patients with 48% or more androgen receptor positive cells had a statistically significant better outcome, in terms of both progression free and cause-specific survival, than patients with less than 48% androgen receptor content. Multivariate analysis demonstrated that androgen receptor content, extent of disease and tumor marker response at three months were significant predictors of outcome.
Conclusions: Androgen receptor content measured immunohistochemically is a useful prognostic indicator for patients with Stage D2 prostate carcinoma treated with endocrine therapy.