Standardizing lymph nodal sampling for Wilms tumor: A feasibility study with outcomes

Abstract

Background: Despite being mandated by cooperative groups, omission of nodal sampling is the most frequent protocol deviation in surgery for Wilms tumor. The stations as well as the number of nodes that should be sampled are not clearly defined resulting in a marked variation in practices among surgeons. We propose a systematic method for nodal sampling intending to reduce interoperator variation. In this study, we have assessed the feasibility and yield of systematic lymph node sampling and also evaluated the factors influencing nodal metastasis.

Methods: Prospective evaluation of 113 Wilms tumor patients operated at a single tertiary cancer center between 2015 and 2019. All these patients underwent a systematic 5-station nodal sampling.

Results: Median lymph node yield was 8 and 13.2% (15/113) patients harbored a histologically positive nodal disease. Of the patients with positive nodal disease, interaortocaval nodes had metastasis in 46.7% (n = 7). They represented isolated sites of nodal disease (skip metastases) in 28.6% (n = 4) of patients. Right-sided tumors had more frequent involvement of interaortocaval nodes and skip disease. Tumors with high-risk histology had 12.5 times more odds of harboring nodal disease as compared to low and intermediate-risk histology Wilms tumor.

Conclusions: The proposed method of systematic station wise sampling provides a template to guide surgeons in performing lymph node harvesting. Interaortocaval nodes sampling should be performed routinely as the incidence of disease at this station is sufficiently high and metastasis may skip hilar nodes.

Study of diagnostic test: Level III evidence.

Keywords: Lymph node; Lymph node metastases; Lymph node sampling; Staging; Template; Wilms tumor.