Prognostic factors in adolescents and young adults (AYA) with high-risk soft tissue sarcoma (STS) treated by adjuvant chemotherapy: A study based on two pooled European Organisation for Research and Treatment of Cancer (EORTC) clinical trials

Abstract

10573 Background: We conducted a retrospective study pooling data from two clinical trials in high risk STS patients with the objective to compare two different age groups: 15 - 29 years (AYA population) and ≥ 30 years. The aim was to determine prognostic factors for the AYA population. Methods: Patients selected for analysis were treated in two randomized trials of adjuvant chemotherapy in STS (EORTC 62771 and 62931). A total of 793 patients were included with a median follow-up (FU) of 8.74 years (AYA population: n = 161, median FU 9.46 years; patients ≥ 30 years: n = 632, median FU 8.62 years). Study endpoints were overall survival (OS) and relapse-free survival (RFS). The variables of the multivariate analysis were gender, subtype and grade, tumor size and localization (limb vs. other), absence or presence of local recurrence and treatment (control arm vs. adjuvant chemotherapy). Results: Patients’ characteristics were globally similar with two exceptions, histological subtype (p = 0.0043) and tumor size (p < .0001). The commonest sarcoma subtype in the AYA population was synovial sarcoma (29 %), whereas leiomyosarcoma (18 %), malignant fibrous histiocytoma (MFH, 16 %) and liposarcoma (15 %) were more frequent in patients ≥ 30 years. For OS, independent favorable prognostic factors were low grade and small tumor size for both groups; radical resection and MFH or liposarcoma subtype were factors of favorable prognosis for patients ≥ 30 years only. For RFS, favorable prognostic factors were small tumor size and low grade for both groups; tumor location in the extremities was a factor of favorable prognosis for the AYA population only, whereas radical resection and adjuvant chemotherapy treatment were favorable factors for patients ≥ 30 years only. Conclusions: On the basis of these data, significant differences could be found concerning prognostic factors between the AYA population and older patients. Interestingly, adjuvant chemotherapy was associated with improved RFS only in patients ≥ 30 years. The results may have further implications on the treatment of STS patients in different age groups as well as the design of future clinical trials. No significant financial relationships to disclose.