KEYWORDS: Renal cell carcinoma; Nephron-sparing surgery; Cancer recurrence CORRESPONDENCE: Sarel Halachmi MD, INTRODUCTION:Tumor recurrence following nephron-sparing surgery (NSS) for renal carcinoma is a major concern.The aim of this retrospective study was to assess the rate, patterns, and predictors of tumor recurrence in patients following NSS for renal cancer. METHODS: Between 1993 and 2008, 229 patients underwent NSS via flank incision for renal cell carcinoma. Patients without metastases at diagnosis (using CT and bone scan) were included in the outcome analysis. Categorical variables were compared with the Fisher-Irwin exact test. Kaplan-Meier was used to determine the probability of overall survival and probability of recurrence curves; significance was tested with the log-rank. The Cox hazard survival model was used to identify whether any of the demographic or clinical variables were predictive of the probability of recurrence. RESULTS: During a mean (SD) follow-up time of 45 (34) months, tumor recurrence was observed in 13 patients (5.6%). Mean follow-up time for detection of oncological failure was 51 months. All patients with oncological failure were males, with a mean age of 61 years (median 58; range, 51-74 years). The average size of the enucleated lesion was 5 cm (range, 4-7 cm). Intraoperative frozen sections and postoperative pathological examination of the surgical margins were negative in all cases. Predictors of oncological failure included: warm ischemia time > 20 minutes (P = .012), tumor size ≥ 4 cm (P = .001), central tumor location (P = .015), multifocal tumors (P =.001), and male gender (P = .01). The probability of overall disease recurrence at 12 and 60 months was 1.8% and 4.0%, respectively. The overall cancer-specific survival rate was 93.8%. The 12-month and 60-month metastasisfree survival rates were 99.1% and 98.4%, respectively. Recurrence was due to surgeon-related and tumor-related patterns. CONCLUSIONS: NSS is an effective surgery with satisfactory long-term cancer control. Predictors of recurrence were consistent with previous literature except for warm ischemia time > 20 minutes (noted for the first time). Reasons for cancer relapse include seeding during surgery, residual disease, distant dissemination, and new tumor growth. Careful tumor handling and extensive perirenal fat resection are within the surgeon's control and may reduce failure rates. UroToday International Journal ® UI J