Abstract
Purpose The incidence of Ewing sarcoma varies according to race and ethnicity, and genetic susceptibility is known to affect disease risk. Apart from these factors, the etiology of Ewing sarcoma is largely unknown. Methods We compared the birth characteristics of a population-based series of 556 Ewing sarcoma cases born in California in 1978–2015 and diagnosed in 1988–2015 with those of 27,800 controls selected from statewide birth records and frequency-matched to cases on the year of birth, using multivariable logistic regression models. We also assessed whether Ewing sarcoma clustered within families. Results Compared to non-Hispanic White subjects, Black (odds ratio [OR] = 0.07, 95% confidence interval [CI] 0.03–0.18), Asian (OR = 0.57, 95% CI 0.41–0.80), and Hispanic (OR = 0.73, 95% CI 0.62–0.88) individuals had a significantly lower risk of Ewing sarcoma. Race and ethnicity differences were more profound for metastatic Ewing sarcoma. Birthweight was also identified as a significant risk factor (OR = 1.09, 95% CI 1.00–1.18 for each 500 g increase in birthweight). A separate family-based cancer clustering analysis did not suggest any strong role for familial predisposition alleles. Conclusions This population-based study with minimal selection bias provides support for a role of accelerated fetal growth in the etiology of Ewing sarcoma in addition to more precise estimates of racial and ethnic variations in disease risk. This comparatively large analysis of birth characteristics and Ewing sarcoma in a multiethnic population should stimulate further investigations into genetic and environmental causes.