Clinicopathologic traits and prognostic factors associated with pediatric sinonasal rhabdomyosarcoma

Background: Pediatric sinonasal rhabdomyosarcoma (RMS) is an aggressive and rare malignancy. This is the first multi-institutional study on the prognostic factors associated with outcomes in this population.

Methods: The National Cancer Database was queried for the period from 2004 to 2013 for all cases of malignant sinonasal RMS in the pediatric population. The impact of patients' demographics, tumor characteristics, and Intergroup Rhabdomyosarcoma Study Group (IRSG) staging on survival was assessed using chi-square test, Fisher's exact test, Kaplan-Meier test, and Cox regression analyses.

Results: A total of 157 cases of pediatric sinonasal RMS were identified. Mean age at diagnosis was 9.38 years and male patients comprised 48.4% of the cohort. The nasal cavity (31.8%) and maxillary sinus (30.6%) were the most common primary sites. Alveolar was the most common histology (49.7%), followed by embryonal type (32.5%). The majority of patients received solely chemoradiation (52.9%), followed by surgery with adjuvant chemoradiation (30.6%). Five-year overall survival (OS) was 55.2% (±4.5%). Metastatic disease was associated with a poorer 5-year OS rate (24.4% vs 61.5%; p = 0.010). Maxillary sinus site was associated with an improved survival (71.8% vs 47.6%; p = 0.009). On multivariate analysis, chemoradiation with or without surgery was an additional prognostic factor. Although IRSG clinical stages did not correlate with survival, high-risk patients in the IRSG clinical risk groups were associated with poorer survival on multivariate analysis (hazard ratio [HR], 2.005; 95% confidence interval, 1.007-3.993; p = 0.048).

Conclusion: To date, this is the largest study on pediatric sinonasal RMS. IRSG clinical risk groups may be useful in stratifying high-risk patients with poor prognosis.