Outcome of localized blastemal-type nephroblastoma patients treated according to intensified treatment in the SIOP 2001 protocol: A report of the SIOP-RTSG.

10002 Background: From previous pre-surgery chemotherapy based SIOP protocols, blastemal type Wilms tumor (BT-WT) has been identified as a poor prognostic subgroup. Therefore in SIOP 2001, post-operative treatment for BT-WT was prolonged and intensified (VCR/Act/Dox in stage I, VP16/Carbo/Cyclo/Dox in stage II-IV) aiming to improve survival. Here, we present characteristics and outcome of BT-WT patients treated on intensified regimen in SIOP 2001. Methods: Response and survival analysis of unilateral BT-WT (n = 238) patients treated from 2001-2012 (SIOP 2001) were compared with SIOP 93-01 (n = 113). Results: In SIOP 93-01 and SIOP 2001 trials, among 4061 unilateral non-metastatic Wilms tumor patients registered, 351 (8.6%) were BT-WT. Median age at diagnosis was 43 months (IQR 24-68). Stages were: I (n = 140, 40%), II (n = 106, 30%), III (n = 105, 30%). Pre-surgery chemotherapy reduced tumor volume from median 359 ml (IQR 174-611) to 123 ml (IQR 41-291). BT-WT were older, higher staged and showed less mar...