DNA cytometric proliferative index predicting organ confinement in clinical stage-B prostate cancer

PURPOSE: To assess nuclear activity by DNA flow cytometry (FCM), Gleason score and serum prostate-specific antigen (PSA) levels in predicting extracapsular tumour involvement in patients with prostate cancer. DESIGN: Retrospective pathologic study. PATIENTS: Forty patients with clinical stage-B prostate cancer who underwent radical prostatectomy. INTERVENTIONS: The relationship between the pathologic state and each of the proliferative index (PI). Gleason score and PSA level was analysed retrospectively with the use of archival specimens. Preoperative serum PSA levels, were measured by the Hybritech assay. Gleason score was determined by 2 of the authors. Tumours were classified as stage B (confined to prostate), C1 (focal capsular penetration) or C2 (involvement of seminal vesicles or capsular perforation). FCM PI measurements were performed on deparaffinized tumour specimens. RESULTS: All 40 specimens were diploid. There were 9 pathologic stage-B, 16 stage-C1 and 15 stage-C2 tumours. The serum PSA level was 20 ng/mL or less for all patients except 2, for whom the levels were 27.8 ng/mL and 45.9 ng/mL, respectively. A Gleason score lower than 7 had a 76.0% sensitivity and 53.5% specificity in predicting organ confinement. In contrast, a PI of 21 or lower had a 84.0% sensitivity and a 73.0% specificity in predicting organ confinement, with a positive predictive value of 84.0%. Of the 17 tumours with both "favourable" features (Gleason score lower than 7 and PI of 21 or lower), only 1 (5.9%) had extracapsular involvement (stage C2). Of the 6 tumours with both "unfavourable" features (Gleason score higher than 7 and PI of 21 or higher) 5 of 6 were stage C2 and 1 was stage C1. CONCLUSION: The single most consistent predictor of organ confinement was PI alone.