Impact of lymph node evaluation in adjuvant and neoadjuvant chemotherapy settings on survival outcomes in Wilms tumour: a review of 185 cases from a single institution.

It is unclear if lymph node sampling in Wilms tumour, though critical for staging purposes, affects survival outcomes. The value of lymph node sampling in patients treated with neoadjuvant chemotherapy (NAC) is even more uncertain. We reviewed our institutional data to determine the impact of lymph node sampling on survival, as well as its role in the context of NAC. A total of 185 patients with Wilms tumour treated at our institution were included in this analysis. The number of nodes sampled (≤7, or >7), lymph node status (unknown, negative, or positive), pathological stage, and use of neoadjuvant chemotherapy were analysed for survival outcomes. Covariates were evaluated with chi-square test or Fisher's exact test where appropriate. All analyses were performed using SAS 9.3 and R package version 2.15.2 with a significant level of 0.05. Median follow-up for all patients was 7.1 years. The number of lymph nodes sampled was significantly related to lymph node status (p<0.001). Lymph node involvement portended worse overall survival after controlling for stage and histology. Patients treated with NAC had higher rates of 'unknown' lymph node status (p<0.001) and worse overall survival than their counterparts (p=0.002); within this group, patients with 'unknown' lymph node status had significantly worse survival than those with negative or positive lymph node. Our data support the available evidence that sampling of more than seven lymph nodes is necessary for adequate staging of Wilms tumour. This is especially critical in patients treated with NAC, who had worse overall survival, likely due to understaging and undertreatment. These findings should be confirmed prospectively to provide proper guidelines to physicians caring for patients with Wilms tumour.