The predictive value of 2-year posttreatment biopsy after prostate cancer radiotherapy for eventual biochemical outcome

PURPOSE: To determine the value of a 2-year post-radiotherapy (RT) prostate biopsy for predicting eventual biochemical failure in patients who were treated for localized prostate cancer. METHODS AND MATERIALS: This study comprised 164 patients who underwent a planned 2-year post-RT prostate biopsy. The independent prognostic value of the biopsy results for forecasting eventual biochemical outcome and overall survival was tested with other factors (the Gleason score, 1992 American Joint Committee on Cancer tumor stage, pretreatment prostate-specific antigen level, risk group, and RT dose) in a multivariate analysis. The current nadir + 2 (CN + 2) definition of biochemical failure was used. Patients with rising prostate-specific antigen (PSA) or suspicious digital rectal examination before the biopsy were excluded. RESULTS: The biopsy results were normal in 78 patients, scant atypical and malignant cells in 30, carcinoma with treatment effect in 43, and carcinoma without treatment effect in 13. Using the CN + 2 definition, we found a significant association between biopsy results and eventual biochemical failure. We also found that the biopsy status provides predictive information independent of the PSA status at the time of biopsy. CONCLUSION: A 2-year post-RT prostate biopsy may be useful for forecasting CN + 2 biochemical failure. Posttreatment prostate biopsy may be useful for identifying patients for aggressive salvage therapy.