ATRT-06. RESULTS OF MULTICENTER TRIAL CONCERNING THE TREATMENT OF CHILDREN WITH ATYPICAL TERATOID RHABDOID TUMORS OF THE CENTRAL NERVOUS SYSTEM UNDER 3 YEARS OLD

Abstract Objective To evaluate the prognostic factors in children with AT/RT aged under 3 years. Patients and methods: The prognostic factors were analyzed in 106patients under 3 years who got treatment and follow-up from 2008 to 2020.There were 41children younger than 12 months and 65patients older than 12 months. The location of the tumor was infratentorial in 58 patients, supratentorial in 46, and spinal cord in 2. There were 54 boys and 52 girls. Among the patients,57 had stage M0,36 had stage М+ or a multifocal tumor, and 13 had stage Mx. All the patients had undergone surgical treatment: total tumor removal in 27, subtotal-33, partial-42, biopsy - 4;67patients had got chemoradiotherapy according to the ATRT-2006(IRS III) protocol; 15, MUV-ATRT protocol; 3, CWS protocol; 9, EU-RHAB protocol; 6, HIT-SKK protocol; and 6 according to individual treatment schemes.12 patients received HDC with AuHCR. Results 47 are alive,1 was lost to follow-up, and 58 died:52 of progressive disease,6 of chemotherapy complications. The five-year PFS was 0.27; the five-year OS was 0.40. The PFS was significantly better in patients older than 12months old compared to patients under 12months: 0.33 and 0.17, respectively; p=0.0047. The PFS after total resection was higher than after subtotal resection, partial resection, and tumor biopsy: 0.51, 0.29, 0.09, and 0%, respectively (p=0.025).The PFS after radiotherapy was markedly higher compared to patients without radiotherapy: 0.63 and 0.0, respectively (р<0.001). The tumor location, stage, and gender did not affect the PFS. The survival rate was statistically significantly higher among the patients who had got treatment according to the ATRT-2006 protocol compared to MUV-ATRT,EU-RHAB, individual therapeutic regimens, CWS, and HIT-SKK: 0.33, 0.26, 0.11, 0.30, and 0.0, respectively; p=0.0020. The PFS was higher among the patients who had got intraventricular/intrathecal chemotherapy; p=0.0002. HDC with AuHCR did not statistically affect the PFS; p=0.0546.In multivariate analysis, the PFS was influenced by the age, tumor location, extent of surgery, radiotherapy, regional chemotherapy, HDC with AuHCR. Conclusions The survival of patients with CNS AT/RT aged under 3years significantly depended on the patients’ age, extent of surgery, chemotherapy protocol, radiotherapy, and regional administration of chemotherapeutic drugs.