Malignant rhabdoid tumours of the kidney (MRTKs), registered on recent SIOP protocols from 1993 to 2005: A report of the SIOP renal tumour study group

+Background: Survival data of malignant rhabdoid tumour of the kidney (MRTK) registered in SIOP trials, advocating preoperative chemotherapy, are not available. Aim To evaluate characteristics, response and survival of MRTK patients registered in recent SIOP protocols. +Methods: An evaluation of all MRTK patients treated from 1993 to 2005 (SIOP trials 93-01 and 2001) was performed. Data were obtained from study specific case record forms and entered centrally in a database. +Results: Hundred and seven patients were identified (57 male), with a median age at diagnosis of 13months (interquartile range 6-27months), and a median follow-up time of 60 months. Left and right kidneys were equally affected. Tumour stage distribution was stage I (6%), stage II (22%), stage III (43%), stage IV (22%) and stage V (3%). Stage IV patients included 17 with pulmonary metastasis (8 lung-only) and 12 with multiple organ metastases (bone, brain and liver). Primary surgery was the upfront treatment approach in 22/107 patients (21%), by which 19 patients reached a complete remission (CR). Median difference in tumour volume before and after preoperative chemotherapy was 69ml (interquartile range: 4.5-158.0, P<0.0001), indicating marked chemosensitivity. The 5-year event-free survival (EFS) of the total group was 22% (95% CI: 15-33) and overall survival 26% (95% CI: 18-37). Most events (86%) occurred within the first 2years after diagnosis. Younger age at diagnosis was an important adverse prognostic factors for survival. In contrast, tumour volume at diagnosis, nor volume reduction was associated with outcome. +Conclusion: MRTK has a poor outcome especially in young and advanced-stage disease patients. Neither tumour volume at diagnosis, nor pre-operative chemosensitivity are prognostic factors for survival.