Objective: Tumour features were evaluated during intermittent androgen suppression (IAS), and their prognostic impact on the first off-treatment time was analysed.
Patients and methods: Twenty patients with advanced prostate cancer underwent three consecutive prostate biopsies during the first cycle, namely at the beginning of androgen deprivation, 8 months after continuous therapy and at the time of prostate-specific antigen (PSA) progression above 20 ng/ml. Biopsy specimens were immunohistochemically processed and analysed for the apoptotic index (AI), Ki-67, p53 and Bcl-2 to investigate eventual changes over time. Correlations and regression analysis were performed to assess the prognostic significance of clinical and pathological parameters in predicting the first off-treatment time.
Results: In contrast to the AI, p53 and Bcl-2, Ki-67 was the only marker that significantly changed over time (P=0.008). The first off-treatment time correlated significantly with pretreatment PSA (r=-0.594; P<0.01), testosterone recovery time (r=0.590; P=0.013) and biopsy grade (r=-0.738; P<0.01); only the latter gaining an independent factor in the multivariate analysis (P=0.022).
Conclusions: During IAS, Ki-67 was the only molecular marker that consistently changed over time. However, it did not correlate with off-treatment time that was predicted independently by the initial biopsy grade only. First off-treatment time was best predicted by clinical parameters and molecular markers from needle biopsies did not further contribute to a better patient selection.