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 13 months (interquartile range 6-27 months), 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 69 ml (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 2 years 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.