Outcome after resection of occult and non-occult lymph node metastases at the time of nephrectomy

Purpose There is sparse evidence on outcomes of resected occult LN metastases at the time of nephrectomy (synchronous disease). We sought to analyse a large international cohort of patients and to identify clinico-pathological predictors of long-term survival. Materials and methods We collected data of consecutive patients who underwent nephrectomy and LND for T-any cN0-1pN1 and cM0-1 RCC at 7 referral centres between 1988 and 2019. Patients were stratified into four clinico-pathological groups: (1) cN0cM0-pN1, (2) cN1cM0-pN1(limited, 1-3 positive nodes), (3) cN1cM0-pN1(extensive, > 3 positive nodes), and (4) cM1-pN1. Overall survival (OS) was estimated using the Kaplan-Meier method, and associations with all-cause mortality (ACM) were evaluated using Cox models with multiple imputations. Results Of the 4370 patients with LND, 292 patients with pN1 disease were analysed. Median follow-up was 62 months, during which 171 patients died. Median OS was 21 months (95% CI 17-30 months) and the 5-year OS rate was 24% (95% CI 18-31%). Patients with cN0cM0-pN1 disease had a median OS of 57 months and a 5-year OS rate of 43%. 5-year OS (median OS) decreased to 29% (33 months) in cN1cM0-pN1(limited) and to 23% (23 months) in cN1cM0-pN1(extensive) patients. Those with cM1-pN1 disease had the worst prognosis, with a 5-year OS rate of 13% (9 months). On multivariable analysis, age (p = 0.034), tumour size (p = 0.02), grade (p = 0.02) and clinico-pathological group (p < 0.05) were significant predictors of ACM. Conclusion Depending on clinico-pathological group, grade and tumour size, 5-year survival of patients with LN metastases varies from 13 to 43%. Patients with resected occult lymph node involvement (cN0/pN1 cM0) have the best prognosis with a considerable chance of long-term survival.