Racial and ethnic differences in presentation and clinical outcomes for pediatric rhabdomyosarcoma (RMS).
Authors: Ekpo Princess , Munnikhuysen Senna Rae , Xue Wei , Gao Zhengya , Venkatramani Rajkumar , Heske Christine M 
Published: June 2022

10017 Background: Race and ethnicity are recognized risk factors for many cancer types, including several pediatric cancers. Though racial and ethnic disparities in the presentation, treatment, and survival of certain cancers have been widely demonstrated, there is conflicting evidence about whether such disparities exist in RMS, the most common pediatric soft tissue sarcoma. Understanding the role of race and ethnicity in the presentation, treatment, and prognosis of RMS is important to promote improved survival in patients of all racial and ethnic groups. Methods: Patient, tumor, and treatment characteristics of patients enrolled on Children’s Oncology Group studies D9602, D9802, D9803, ARST0331, ARST0431, ARST0531, and ARST08P1 were compared across racial and ethnic groups using a chi-square test. Significant characteristics underwent pairwise analysis, comparing the Non-Hispanic Black (NHB) and Non-Hispanic White (NHW) groups. Outcome analyses were performed using the Kaplan-Meier method and Wilcoxon signed-rank test. Results: Race and ethnicity incidence among the 2157 study patients were as follows: 8 (0.4%) American Indian or Alaska Native, 56 (2.6%) Asian, 271 (12.6%) Hispanic, 4 (0.2%) Native American or other Pacific Islander, 275 (12.8%) Non-Hispanic Black, 1335 (61.9%) Non-Hispanic White, and 208 (9.6%) unknown. Thirteen patient and tumor factors relating to presentation and treatment were evaluated for differences by race and ethnicity; the following five were significant: age, IRS group, tumor invasiveness, metastatic disease, and FOXO1 fusion partner. Pairwise comparison of NHB and NHW patients for these factors demonstrated that NHBs are more likely than NHWs to present at age 10 years or greater (p = 0.002) and that NHB patients are more likely to present with invasive tumors (p = 0.012). Incidence of metastatic disease at diagnosis was not significantly different between the groups (p = 0.202). No differences in treatment, including extent of surgical resection (p = 0.259) or use of radiation therapy (p = 0.920), were found. Neither event free survival nor overall survival were significantly different across the entire cohort (EFS p = 0.457, OS p = 0.159) or in subset analysis by risk group (low risk: EFS p = 0.856, OS p = 0.558; intermediate risk: EFS p = 0.907, OS p = 0.493; high risk: EFS p = 0.218, OS p = 0.397), by age (< 1y: EFS p = 0.489, OS p = 0.546; 1-9y: EFS p = 0.417, OS p = 0.112; ≥10y: EFS p = 0.556, OS p = 0.609), in invasive tumors (EFS p = 0.704, OS p = 0.872), or in metastatic disease (EFS p = 0.270, OS p = 0.373). Conclusions: These data indicate that while differences in the presenting features of RMS exist between racial groups, with NHB patients exhibiting higher risk features, patients treated on these clinical trials did not experience differences in outcomes by racial group. This suggests NHB patients may experience a survival benefit from clinical trial enrollment.