Maternal and birth characteristics and childhood rhabdomyosarcoma: a report from the Children's Oncology Group.

Purpose: Previous assessments of childhood rhabdomyosarcoma have indicated maternal and birth characteristics may be associated with tumor development; however, much work remains to identify novel and confirm suspected risk factors. Our objective was to evaluate the associations between maternal and birth characteristics and childhood rhabdomyosarcoma.

Methods: This case-control study included 322 cases and 322 pair-matched controls. Cases were enrolled in a trial run by the Intergroup Rhabdomyosarcoma Study Group. Population-based controls were identified using random digit dialing and were individually matched to cases on race, sex, and age. Families of the case and control subjects participated in a telephone interview, which captured information on maternal characteristics (birth control use, number of prenatal visits, anemia, and abnormal bleeding during pregnancy) and birth characteristics [birth weight, preterm birth, and type of delivery (vaginal vs. cesarean)]. Conditional logistic regression models were used to calculate an odds ratio (OR) and 95% confidence interval (CI) for each exposure, adjusted for age, race, sex, household income, and parental education. As the two most common histologic types of rhabdomyosarcoma are embryonal (n = 215) and alveolar (n = 66), we evaluated effect heterogeneity of these exposures.

Results: The only characteristic that was associated with childhood rhabdomyosarcoma, and statistically significant, was abnormal vaginal bleeding during pregnancy (OR 1.75, 95% CI 1.12-2.74). Birth control use (OR 1.45, 95% CI 0.96-2.18), anemia during pregnancy (OR 1.27, 95% CI 0.81-1.99), and preterm birth (OR 2.51, 95% CI 0.74-8.49) were positively associated with childhood rhabdomyosarcoma, but were not statistically significant. Low birth weight [adjusted odds ratios (aOR) 4.46, 95% CI 1.41-14.1] and high birth weight (aOR 2.41, 95% CI 1.09-5.35) were strongly associated with alveolar rhabdomyosarcoma. However, these factors did not display significant effect heterogeneity between histologic types (p > 0.15 for all characteristics).

Conclusions: Overall, we found little evidence that these maternal and birth characteristics are strongly associated with childhood rhabdomyosarcoma.