Patterns of toxicities and outcome in children versus adolescents/young adults (AYA) with metastatic rhabdomyosarcoma (RMS): A report from the Children’s Oncology Group (COG) Soft Tissue Sarcoma Committee.

Abstract

10554 Background: Age at diagnosis is a prognostic factor in patients with RMS. We sought to determine whether AYA with metastatic alveolar (ARMS) or embryonal (ERMS) RMS had a different failure-free survival (FFS) compared to younger patients, and to identify treatment related factors that may be associated with outcome. Methods: COG ARST0431 patients were reviewed. The incidence of toxicities (AE, grade3/4 using CTCAEv3) by age was determined in 4 reporting periods (RP: wks 1-6; RP2:7-19; RP3: 20-34; RP4: 35-54). The AEs in younger patients (<=13 years) were compared with those in AYA. Fisher’s exact test was used to compare differences between the groups. Results: Of 109 patients, 60 (55%) were AYA. In RP1, they were more likely to have nausea/vomiting (4.1 vs. 16.9%, p=0.06), pain (6.1 vs. 20.3%, p=0.05), and metabolic disturbances (4.1 vs. 20.3%, p=0.02) compared to younger patients. In RP4, older patients trended to have less infection (15.8 vs. 30.1, p=0.07). All other toxicities were similar between the two age cohorts in the other RPs. AYA were less likely to complete therapy (52 vs. 73%, p=0.03) and more likely (in RP 4) to have unplanned dose modifications (outside of protocol guidelines) (23 vs. 2.7%). Of patients that completed therapy, there was no age-related difference in the time to completion. As shown in the table, younger patients had better 3-yr FFS, driven by a lower FFS for AYA with ARMS. Conclusions: This evaluation suggests that AYA with RMS were less likely to complete therapy and experienced a higher prevalence of pain and nausea compared to younger patients; the role of reporting bias and reasons for treatment discontinuation need further study. Children were more likely than AYA to have infection. Inferior FFS was only seen in AYA with ARMS suggesting a clear need for novel therapies for these patients. This study may be underpowered to demonstrate significant differences in other toxicities or in FFS among ERMS patients. [Table: see text]