Local Stage dependent necessity of Radiotherapy in Rhabdoid Tumors of the Kidney (RTK) - the GPOH experience.

Abstract Background Rhabdoid tumor of the kidney (RTK) is one of the most aggressive childhood renal tumors. Overall survival ranges from 22 to 47%. Indication for radiotherapy (RTx) in usually very young patients is an ongoing discussion. Recent protocols recommend RTx independent of local stage, the latter being a good discriminator in other childhood kidney tumors. Here we analyze the evidence for RTx with respect to risk factors including tumor stage. Methods Analysis of 58 patients with RTK from Austria, Switzerland and Germany treated in the framework of four consecutive, prospective renal-/rhabdoid tumor-studies from 1991 to 2014. All treatment protocols included multimodality treatment including high intensity chemotherapy, surgery and RTx. Results Local stage distribution was (not applicable/I/II/III): 1/6/11/40. 29(50%) patients had stage IV disease at diagnosis. 37(64%) achieved complete-remission, 49% (18/37) relapsed. 34(60%) patients had progressive disease (PD) and died, 17 local, 10 combined and 7 distant; two treatment related deaths were reported (3%). 21 patients received RTx during first-line treatment, 18 of them to all involved sites. 8 of 34 PD occurred in irradiated patients. Local failure rate of treated patients with local stage II or III was 29% (6/18) in patients irradiated to all sites compared with 68% (15/22) in non-irradiated patients. One of 6 stage-I patients received RTx and one patient suffered from distant relapse (2y PFS/OS both 83(±15)%). PFS for local stage II and III treated with RTx, adjusted for early relapse or treatment abandonment, was 67(±11)%, compared to 15(±7)% without RTx (p Conclusion 68% local failure rate in non-irradiated patients underlines the importance of local treatment. Our experience supports the use of RTx for local control in higher stage disease. In contrast, no local relapse in 6 local stage I patients, including 5 non-irradiated, suggests omission of RTx in this favorable subset of usually infant-RTK-patients.