Prevalence and impact on survival of positive surgical margins in partial nephrectomy for renal cell carcinoma: a population-based study.

Abstract

To determine the prevalence of positive surgical margins (PSMs) on a population level. To identify the predictors of PSMs and assess their impact on survival. Using the Ontario Cancer Registry, we reviewed pathology reports on 664 patients after partial nephrectomy for renal cell carcinoma between 1995 and 2004. Demographic information and pathological characteristics were obtained and multivariable logistic regression analysis was performed to determine the predictors of PSMs. Kaplan-Meier analysis was used to examine disease-specific (DSS) and overall survival (OS) by margin status. A multivariable Cox proportional hazards model was used to determine the independent association between PSMs and survival. The mean patient age was 57.7 years and 61.6% were men. Tumour size was <2.0 cm in 25%, 2.0-3.9 cm in 59%, 4.0-6.9 cm in 13%, and ≥7.0 cm in 3% of patients. Seventy-one patients (10.7%) had PSMs on final pathology. Only stage (P = 0.02) and fat invasion (P = 0.04) were significantly associated with PSMs. At a median follow-up of 7.9 years, the unadjusted 5-year DSS and OS rates were 91.8 and 88.3%, respectively. Survival rates did not differ by surgical margin status, with 90.9 and 84.4% 5-year DSS and OS rates for patients with PSMs compared with 91.9 and 88.6% for those with a negative surgical margin (P = 0.58, log rank test). Using a Cox proportional hazards model, surgical margin status was not associated with time to all-cause death (P = 0.67). Our population-level data suggest that, although PSMs are fairly prevalent, they appear to have little to no impact on 5-year survival rates.