Positive surgical margins after partial nephrectomy for renal cell carcinoma: Results from Canadian Kidney Cancer Information System database.

420 Background: Partial nephrectomy (PN) is the standard of care for small renal masses (SRMs) whenever feasible. The occurrence of a positive surgical margin (PSM) on a pathological specimen is not uncommon and an ideal management is unknown. We conducted this study to examine the rate of PSM, predictors of PSM and their oncological outcomes after PN for renal cell carcinoma (RCC), using the Canadian Kidney Cancer information system (CKCis) database. Methods: We accessed the prospectively maintained CKCis database for 1066 patients who underwent PN for RCC in major academic centers all across Canada. Demographics, clinical, pathological and follow-up data were noted for patients with PSM and negative surgical margins (NSM). Multivariate logistic regression analysis was performed to assess predictors of PSM. Results: Out of 1066 patients, 59 (5.5%) had PSM, 928 (87%) had NSM and records of 79 (7.4%) patients were not available. Mean patient age was 61 years and 59 years in the PSM and NSM group respectively, and in each group 63% of the patients were males. Mean tumor size was 3.6cm (range 1.1 – 9.5) and 3.3cm (range 0.5 – 16.2) in PSM and NSM group respectively. PSM group had 5 (8%) grade 1, 28 (47%) grade 2, 16 (27%) grade 3 and 5 (8%) grade 4 tumors as compared to 127 (14%), 458 (50%), 207 (23%) and 27 (3%) respectively in NSM group. Four (6.7%) patients from the PSM group and 49 (5.3%) patients from the NSM group had local and/or systemic progression of disease. There were two cancer specific deaths in NSM group and none in PSM group. Fifty two (88%) and 861 (93%) patients were alive at mean follow-up of 18.5 (range 0 – 91.7) and 28.9 months (range 0 – 315.5) in PSM and NSM group respectively. For the multivariate logistic regression analysis; Fuhrman grade 4 predicted presence of PSM whereas age, operative technique, tumor size, tumor stage did not. Conclusions: Results from the CKCis database suggest that PSM after PN are common but does not result in adverse oncological outcomes. Presence of Fuhrman grade 4 may be associated with PSM on final pathological specimen.