Reevaluation of prostate biopsy after definitive radiation therapy.

We have previously reported (1987) that a positive biopsy from a clinically normal prostate eighteen months or more after interstitial Iodine 125 or external beam irradiation predicted disease progression. In the present study, all biopsies were reexamined by the same pathologist (LEL) and correlated with long-term patient status. Of twenty-six positive biopsy specimens, twenty-two were reconfirmed as positive and four were reassigned to a negative diagnosis (false positive = 15%). Seventy-two of seventy-seven negative specimens were available for reexamination and seventy were reconfirmed as negative while two were reassigned to a positive diagnosis (false negative = 2%). A statistically higher incidence of local and/or distant failure for patients with positive biopsy specimens compared with patients with negative biopsy specimens was again confirmed (p = < 0.001). However, there is a group of patients with a positive biopsy (17%) who remain clinically free of disease at greater than ten years of follow-up. Therefore, a positive biopsy is not an absolute indication of imminent failure. Our results demonstrate the technical difficulty and potential error in interpreting prostate biopsies after radiation therapy. Therapeutic decisions should be based not only on biopsy histology but must also weigh the patient's initial tumor stage and grade, current clinical examination, PSA level, age, and health.