Marcotte EL, Domingues AM, Sample JM, et al. - In the United States, reporting of incidence rates of pediatric cancers is typically done in 5-year age groups, obscuring variation by single year of age. In addition, variation in incidence by race and ethnicity is typically reported in broad categories rather than by narrow age ranges. Researchers herein examined the Surveillance, Epidemiology, and End Results (SEER) 18 data (2000-2017) with the aim to determine frequencies and age-adjusted incidence rates among individuals aged birth to 39 years. Findings revealed substantial variation in race/ethnicity-specific and overall rates by single year of age for several histologic types. Overall, substantially decreased incidence of acute lymphoid leukemia was recorded for Black children and young adults compared with Whites, and this decreased incidence was noted to be strongest at ages 1 through 7 years and 16 through 20 years. Decreased overall incidence of Hodgkin lymphoma and astrocytoma and increased risk of acute lymphoblastic leukemia were recorded for Hispanic individuals vs non-Hispanic Whites, and the increased risk was strongest at ages 10 through 23 years. In addition, they noted substantial decreased risk across many tumor types for Asian/Pacific Islanders and American Indian/Alaska Natives. These findings may provide insights regarding etiological differences in subgroups and may enable hypothesis generation on drivers of disparities observed.