The Prognostic Significance Of Prostate Bed Biopsy In Patients Receiving Post-Prostatectomy Salvage Irradiation

Salvage radiation therapy (SRT) results in a durable relapse-free survival in select patients with a rising prostate specific antigen (PSA) following radical prostatectomy (RP). This study examines the prognostic significance of pre-radiotherapy prostate bed biopsies on the overall (OS) and relapse free survival (RFS) of this group of patients. Between 1991 and 2003, 173 patients were treated with radiation therapy to the prostate bed for a rising PSA after radical prostatectomy. Prior to SRT, no patients had clinical or radiological evidence of metastatic disease. Sixty seven patients had a biopsy prior to radiation therapy (RT) and 98 patients were treated without a biopsy (8 patients with unknown biopsy status). Thirty four patients had a positive biopsy and 33 patients had a negative biopsy. One hundred fifty two patients received photon irradiation (median dose: 6800 cGy) and 21 patients received a combination of photon and neutron irradiation to a median photon equivalent dose of 7800 cGy. A patient was considered to have biochemical failure if his post-nadir PSA level was ≥ 0.2 ng/ml. There were no differences in pre-RP or pre-SRT patient characteristics between the group that had a biopsy and the group that did not. With a median follow-up of 49 months (range: 3–137 months) the 7 year OS was 84% and the 7 year RFS was 44%. There was no difference in either OS or RFS between the patients that had a biopsy and the group that did not (p = 0.69). Among patients who had a biopsy, there was no difference in survival between the biopsy positive and biopsy negative patients (p = 0.55). Logistic regression analysis of factors predicting a positive versus negative biopsy revealed that race and gleason score were associated with a positive biopsy. In addition, patients with a positive biopsy were more likely to have received pre-RT hormones and neutrons, but these factors were not associated with an increased benefit on multivariate analysis. There is considerable debate regarding the necessity and significance of pre-RT biopsy in patients with a rising PSA following radical prostatectomy. These data suggest that a pre-RT prostate bed biopsy does not provide useful information regarding prognosis and probably does not need to be done