Survival disparities for childhood cancers exist when defined by race/ethnicity and sex

1. Introduction

Racial/ethnic differences in pediatric cancer survival have been reported. There are racial/ethnic disparities in acute lymphoblastic leukemia (ALL) survival such that Black children, who have half the rate of ALL incidence of White children, [1] experience worse outcomes than White children [2] and have a higher frequency of high-risk disease features including a higher white blood cell count, a higher proportion of somatic structural chromosomal anomalies, less high hyperdiploidy, and more central nervous system involvement 3456 . A higher risk of death has also been reported in Hispanic and American Indian/Alaska Native children with ALL [7] . For brain tumors, the most common solid tumor in children, [8] minority children have an increased risk of death compared to White children [910] even after adjustment for age, socioeconomic status, stage of disease and treatment [11] . Minority children fare worse than White for pediatric sarcomas [12] . Survival differences have been observed for Black and Hispanic children compared to White with acute myeloid leukemia (AML), neuroblastoma and lymphomas [13] . Often times, racial/ethnic survival disparities are linked to existing differences in socioeconomic status [14] . However, in a mediation analysis examining the role of socioeconomic status (SES) between race/ethnicity and survival from childhood cancers [13] strong direct effects of race/ethnicity were observed suggesting genomics, treatment receipt or response differences may underlie the observed disparities.

We recently reported on sex differences in survival where males had worse overall survival for ALL, ependymoma, neuroblastoma, osteosarcoma, thyroid carcinoma, and malignant melanoma [15] . The observed sex differences in survival could be due to sexually dimorphic tumor profiles as we reported for osteosarcoma, [16] response to treatment, [17] delay in diagnosis [18] or delay in treatment. Given the existing racial/ethnic and sex differences in childhood cancer survival, we conducted stratified analyses by race/ethnicity and sex jointly to better understand the biologic underpinnings of the existing outcome disparities using SEER data for 17 pediatric malignancies. Further, rather than adjust for race/ethnicity in sex-stratified analyses or vice versa, our analytic approach allows us to identify groups that are at an increased risk of death following a childhood cancer diagnosis. Whereas past analyses treated race/ethnicity or sex as an adjustment variable, which may mask effect measure modification of the association between these factors and death after a childhood cancer diagnosis, we are considering both factors for a clearer picture of survival disparities in children with cancer.