Treatment of patients with stage I focal anaplastic and diffuse anaplastic Wilms tumour: A report from the SIOP-WT-2001 GPOH and UK-CCLG studies

Anaplasia is an unfavourable prognostic histological feature in Wilms tumour (WT). Patients with stage I anaplastic WT (AWT) typically achieve good outcomes, albeit with more treatment than for stage I non-AWT. Since the SIOP-WT-2001 study, patients with focal AWT (FAWT) have been classified as intermediate risk and received less intense treatment than patients with diffuse AWT (DAWT). The aim of the study was to analyse outcomes in these patients. This was a retrospective analysis of clinicopathological features and outcomes of 59 patients with stage I AWT (19 FAWT, 40 DAWT) from the SIOP-WT-2001 GPOH and UK-CCLG groups. The patients with FAWT were treated as intermediate-risk WT, with 8 weeks of vincristine and actinomycin D (4 weeks pre-operatively, and 4 weeks post-operatively). For comparison, we also assessed outcomes in 818 patients with stage I intermediate-risk non-AWT (IR-non-AWT). The patients with DAWT were treated with vincristine, actinomycin D and doxorubicin for 31 weeks. No group received radiotherapy. Median follow-up was 67.6 months; 4-year event-free survival and overall survival were 87% (95% confidence interval [CI] = 72–100) and 100%, respectively, in the FAWT group, 85% (95% CI = 74–98) and 93% (95% CI 85–100), respectively, in the DAWT group and 91% (95% CI = 89–93) and 98% (95% CI = 97–99), respectively, in the IR-non-AWT group. Outcomes for patients with stage I FAWT were comparable with those of other, identically treated, patients with stage I IR-non-AWT. Patients with stage I DAWT also showed good outcomes, albeit with more intensive chemotherapy than IR-non-AWT, but without radiotherapy. [Display omitted] •Anaplasia is a powerful prognostic factor in patients with Wilms tumour (WT).•Previously, stage I focal anaplastic WT (FAWT) and diffuse anaplastic WT (DAWT) were treated the same.•In the present study, FAWT was treated as intermediate-risk WT (IR-WT).•FAWT and IR-non-AWT had comparable outcomes.•DAWT showed good outcomes with more intensive chemotherapy but without radiotherapy.