Head and neck embryonal rhabdomyosarcoma clinical outcomes determinates: A pooled database analysis.

Abstract

e23537 Background: Embryonal rhabdomyosarcoma (ERS) is a soft tissue sarcoma of skeletal muscle with mesenchymal precursor cells that involve the genitourinary system or head and neck. Currently, head and neck embryonal rhabdomyosarcoma (HNERS) is considered a similar entity to other ERS subtypes by the Intergroup Rhabdomyosarcoma Study Group (IRSG), with only parameningeal disease being considered as high risk. We seek to identify other higher risk phenotypes in this population. Methods: To study the demographic, molecular and IHC characteristics, therapeutic interventions, survival, and prognostic factors, we compiled a pooled database of 101 cases of HNERS. Kaplan-Meier survival curves, Cox proportional-hazards model and Log-rank tests were used to assess the influence of demographic and clinicopathologic factors on overall survival (OS). Results: 101 patients with confirmed HNERS were identified: median age of 6.5 years, male predominance with M:F ratio of 1.7. While R0 was achieved in 44%, surgical R1 and R2 were feasible in 13% and 44% of the cases. HNERS involved the following anatomic sites: Parameningeal (49%), Skull (40%), Maxilla (39%), Nasopharynx (34%), Ears (25%), Oropharynx (17%), Nervous system (16%), Larynx (14%), Mandible (12%), Internal Jugular (7%), Orbit and Carotids (6% each), Tongue (3%), and thyroid (2%). Lymph nodes, and bone marrow were involved in 11% and 2%, respectively. Metastases occurred in 4%. The stage distribution consisted of stage I (41%), stage II (34%), stage III (19%), and stage IV (6%). Clinical groups comprised: IA(23%), IB(4%), IIA(8%), IIB(3%), IIIA(45%), IIIB(12%), and IVA(4%). Risk groups consisted of low (53%), intermediate (41%), and high (6%). The cohort’s median DFS was 240 months whereas the median OS was not reached. OS was negatively affected by parameningeal (p = 0.01), nasopharyngeal (p = 0.02), ear (p = 0.02), nerve (p = 0.0001), bone (p = 0.002), and LN (p = 0.0004) involvement. The presence of metastases was associated with worse OS (p = 0.0001). The IRSG staging system (p < 0.0001), the risk groupings (p = 0.0001), and the clinical groupings (p = 0.06) correlated with OS, though the latter did not reach statistical significance. Compared to no treatment, localized therapies such as surgery and radiation therapy, and combination chemotherapy had statistically significant improvement in OS (p = 0.027). Achieving CR was associated with superior OS (p < 0.0001). OS wasn't impacted by age, sex, extent of surgery, IHC, BM involvement or other head and neck anatomic site involvement. Conclusions: Embryonal Rhabdomyosarcoma of the Head and Neck is a distinct clinical subtype of ERS not fully defined by IRSG clinical groups when compared to other types of embryonal rhabdomyosarcoma. Parameningeal, nasopharyngeal, ear involvement had poor OS and should be considered as a clinical grouping. This study presents updated data from a pooled cohort of patients with HNERS.