ABSTRACT
There are about thirty articles in the published literature about the pathology of irradiated prostate cancer. This represents 0.3% of all Medline citations on prostate cancer over the past thirty years. Changes after brachytherapy resemble those after external beam therapy, although some findings are peculiar to brachytherapy (see below). The rate of postradiation therapy positive biopsy varies widely, ranging from 19% to 93% based on patient selection factors, the interval from treatment, the number of biopsy samples obtained, the use of other therapies, and, perhaps most importantly, histologic interpretation.1 Factors that determine the likelihood of a positive biopsy include pretreatment clinical stage, cancer grade, posttreatment serum, prostate-specific antigen (PSA), and digital rectal examination. There are three main problems with interpretation: (1) false-negative biopsies resulting from sampling variation; (2) false-positive biopsies due to slow regression of tumor; and (3) biopsies showing residual tumor of indeterminate viability. In this chapter we evaluate the diagnostic criteria for a positive biopsy after radiotherapy and the prognostic significance of these findings. Consideration of the effects of irradiation on the benign prostate serves as a baseline for interpreting changes in cancer.
