Anatomic Pathology / PROSTATE RADIATION The Influence of Percentage of Preradiation Needle Biopsies With Adenocarcinoma and Total Radiation Dose on the Pathologic Response of Unfavorable Prostate Adenocarcinoma

We studied relationships among clinicopathologic factors in 78 patients with unfavorable prostate adenocarcinoma treated in a dose-escalation radiation therapy (RT) study using preand 18-month protocol post-RT biopsy specimens. Pre-RT factors analyzed were serum prostate-specific antigen (PSA) level, Gleason score, and percentage of needle cores with adenocarcinoma; post-RT factors were percentage of needle cores with adenocarcinoma and amount of radiation effect on the adenocarcinoma. Of 78 patients, 42 (54%) had residual adenocarcinoma in the post-RT biopsy specimen. Lower total RT dose and dose per implant and greater serum PSA level were associated with an increasing percentage of needle cores with residual post-RT adenocarcinoma. Lower RT dose, an increasing percentage of pre-RT needle cores with adenocarcinoma, and a greater serum PSA level were associated with an increasing percentage of post-RT needle cores with no to moderate RT effect scores in adenocarcinoma. The mean percentage of pre-RT and post-RT needle cores with adenocarcinoma was greater in patients with post-RT biopsy specimens with no to moderate RT effect. The percentage of pre-RT needle cores with adenocarcinoma (a surrogate marker of adenocarcinoma volume), serum PSA level, and RT dose are the key components in the dose-response relationship. Gleason score and gland volume did not contribute significantly to this relationship. Prostate adenocarcinoma is a biologically diverse disease. Factors associated with a greater risk of metastases, symptoms, and an aggressive clinical course include adenocarcinoma of a higher Gleason score, higher pretreatment serum prostate-specific antigen (PSA) levels, and higher clinical stage.1 Together, these factors identify patients with adenocarcinoma with an unfavorable prognosis for whom there are a limited number of treatment options. External beam radiation therapy (RT) combined with brachytherapy is an effective treatment option for prostate adenocarcinoma with an unfavorable prognosis.2-5 Accumulating experience has substantiated the efficacy and safety of this radiation combination. Computer-generated dosimetry models using computed tomography and transrectal ultrasonography scans provide precise guides and maps for the optimal distribution of radiation throughout the prostate. Despite the sophistication of these integrated technologies, the factors associated with successful local and biochemical control with radiation are poorly understood. The relationships among prostate gland volume, adenocarcinoma volume, adenocarcinoma grade, and radiation dose have not been studied extensively. The William Beaumont Hospital Radiation Oncology Department (Royal Oak, MI) initiated and maintained a doseescalating study of external beam radiation combined with high dose rate (HDR) brachytherapy for patients with prostate adenocarcinoma with an unfavorable prognosis. Part of this protocol has been the performance of prostate needle core biopsies approximately 18 months after completion of the RT. These routine post-RT biopsies are a valuable asset because they serve as an intermediary window by means of which dose-response relationships can be evaluated. Am J Clin Pathol 2002;117:927-934 927 © American Society for Clinical Pathology Goldstein et al / PROSTATE RADIATION We studied clinicopathologic features in 78 patients with prostate adenocarcinoma with an unfavorable prognosis treated with the dose-escalation external beam RT and highdose brachytherapy protocol to identify relationships between prostate adenocarcinoma features, prostate gland volume, and radiation dose. Materials and Methods