The effect of pathologic T-stage and Gleason score on cancer-specific survival in patients with positive surgical margins after surgery for high-risk prostate cancer.
140 Background: High-risk prostate cancer (HRPC) is a challenging disease and the role of surgery is often considered in the context of a multimodal approach but patients with positive section margins (R1) disease have not always the same cancer-specific survival (CSS). The current study aims to analyze current postoperative pathological features in order to predict CSS of HRPC patients with R1, but with negative lymph nodes (pN0), treated with surgery. Methods: From a multi-institutional retrospective cohort of 5,876 HRPC patients treated by radical prostatectomy and pelvic lymph node dissection, 1541 patients with pN0 and R1 were selected. Following surgery, adjuvant EBRT and/or ADT were delivered according to institutional protocols. Patients were subdivided into four groups according to pT stage (pT≥3 and pT<3) and p-Gleason score (pGS≥8 and pGS<8). Kaplan-Meier plots with log-rank tests and a Cox proportional hazards model were applied to study CSS. All significance levels were set at 0.05. MedCalc was used for all statistical analyses. Results: Median age at surgery was 66 years (42-89). Of all patients, 399 (25.9%) had GS≥8 and 999 (64.8%) had pT≥3 at definitive histopathology. Patients were classified as COMBO groups: C1 (423; 27.4%; GS<8,pT<3), C2 (674; 43.7%; GS<8, pT≥3), C3 (83; 5.4%; GS≥8, pT<3), C4 (362; 23.5%; GS≥8, pT≥3). Adjuvant EBRT and ADT, respectively, were delivered in C1 3%/5%, C2 15%/21%, C3 21%/20%, C4 28%/40%. Kaplan-Meier plots demonstrated statistically different 10-yr CSS between groups: C1 97%, C2 93.8%, C3 85.1% and C4 77.3% (p<0.0001). COMBO groups were also compared using a Cox model and results are shown in the Table. Conclusions: COMBO groups demonstrated to be able to subdivide margin-positive, pN0 HRPC into 4 demarcated groups with significantly different CSS. This subdivision could be considered an easy-to-use tool which can help for counseling patients for adjuvant treatment strategies. [Table: see text]