Sporadic childhood Burkitt lymphoma incidence in the United States during 1992–2005

BACKGROUND: The risk factors and co-factors for sporadic childhood BL are unknown. We investigated demographic and age-specific characteristics of childhood BL (0-14 years) in the U.S. PROCEDURE: BL age-standardized incidence rates (2000 U.S. standard population), were calculated using data obtained from 12 registries in the NCI's Surveillance, Epidemiology, and End Results program for cases diagnosed from 1992 to 2005. Incidence rate ratios and 95% confidence intervals (95% CI) were calculated by gender, age-group, race, ethnicity, calendar-year period, and registry. RESULTS: Of 296 cases identified, 56% were diagnosed in lymph nodes, 21% in abdominal organs, not including retroperitoneal lymph nodes, 14% were Burkitt cell leukemia, and 9% on face/head structures. The male-to-female case ratio was highest for facial/head tumors (25:1) and lowest for Burkitt cell leukemia (1.6:1). BL incidence rate was 2.5 (95% CI 2.3-2.8) cases per million person-years and was higher among boys than girls (3.9 vs. 1.1, P < 0.001) and higher among Whites and Asians/Pacific Islanders than among Blacks (2.8 and 2.9 vs. 1.2, respectively, P < 0.001). By ethnicity, BL incidence was higher among non-Hispanic Whites than Hispanic Whites (3.2 vs. 2.0, P = 0.002). Age-specific incidence rate for BL peaked by age 3-5 years (3.4 cases per million), then stabilized or declined with increasing age, but it did not vary with calendar-year or registry area. CONCLUSIONS: Our results indicate that early childhood exposures, male-sex, and White race may be risk factors for sporadic childhood BL in the United States.