Templated Lymph Node Sampling For Pediatric Renal Tumors: Increased Yield Without Increased Complications
Daniel Han, MD1, Andrew Nicklawsky, MS2, Nicholas Cost, MD1, Jonathan P. Walker, MD3.
1University of Colorado School of Medicine, Children's Hospital Colorado, Aurora, CO, USA, 2University of Colorado Cancer Center, Aurora, CO, USA, 3University of Tennessee College of Medicine Chattanooga, Chattanooga, TN, USA.
BACKGROUND: Children’s Oncology Group protocols mandate lymph node sampling (LNS) during surgery for a suspected renal malignancy, but the extent of LNS has not been clearly defined. While data suggest a minimum of 6-10 LNs are needed for accurate staging, LNS is often omitted or underperformed. Concerns over increased morbidity with extended LNS have led to hesitancy adopting a formal LN dissection template. The rate of complications during LNS in pediatric patients is low, and we hypothesized that complications in children undergoing LNS for renal tumors would not differ based on templated vs random LNS and that templated LNS would result in higher LN yield . METHODS: A retrospective review of patients aged 0 - 18yrs undergoing extirpative renal surgery with LNS for a suspected malignancy at a tertiary institution between 2005-2019 was performed. Patients with an unknown number of LNs sampled or whose LNs were not sent as a separate specimen were excluded. Intraoperative and postoperative complications were recorded and categorized based on the Clavien-Dindo (CD) scale. Patients were grouped according to the LNS technique used by the attending surgeon of record: random vs templated. Chi-square and Wilcoxon rank sum were used to assess the relationship between LNS technique and complications, LN count, and disease stage. Kaplan-Meier curves were used to compare disease recurrence between the two cohorts. RESULTS: 150 patients met inclusion criteria. Median patient age was 37.8 months (IQR 20.3-62.4). 96 (64%) underwent random LNS vs 54 (36%) who underwent templated LNS. No difference in complications (p=0.8673) or disease stage (p=0.6392) was seen between the two cohorts. Median LNs sampled was higher in the templated vs random sampling cohort (12 vs 6, p<0.001). 10/96 (10.4%) patients in the random LNS group and 2/54 (3.7%) in the templated LNS group developed disease recurrence (p=0.7042, HR 0.74, 95% CI 0.15- 3.55). CONCLUSIONS: Templated LNS during surgery for pediatric renal tumors does not appear to lead to an increase in complications and results in a higher LN yield. A standardized LNS template for pediatric renal tumors may lead to increased protocol adherence, but more studies are needed to determine if this will result in more accurate staging. With high overall survival rates and low recurrence rates, larger patient cohorts are needed to determine the therapeutic benefit of templated LN sampling on these outcome measures. 
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