Irtan S, et al. - In order to determine the impact of biopsying Wilms tumor (WT) at diagnosis on assigning the tumor stage and recommended treatment, researchers examined patients treated in the SIOP WT 2001 trial, where needle biopsy was permitted without ‘upstaging’ the tumor to stage III, for the potential association of all types of biopsy with local recurrence. Only open biopsy required treatment as stage III. Four hundred twenty relapsed (139 local) were identified among 2971 patients with unilateral WT (stages I-IV). They identified 969 (33%) patients who underwent biopsy (64% cutting needle, 30% fine needle aspiration and 6% open biopsy). Multivariate analysis comprising all factors associated with local recurrence in univariate analysis revealed only high-risk histology, age≥2 years and preoperative tumor volume as significant. They noted no significant hazard ratio for the association of local recurrence and event-free and overall survival with biopsy. This post hoc analysis suggests no independent adverse effect of needle biopsy on either local recurrence or survival after adjustment for all relevant risk factors. They recommend against using needle biopsy as an automatic criterion to ‘upstage’ WT.