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.