Improved survival of Burkitt lymphoma/leukemia patients: observations from Poland, 1999-2020

The aim of this study was to estimate the survival of Polish Burkitt lymphoma/leukemia (BL) patients diagnosed between 1999 and 2017, considering multiple covariates and periods, to reflect changes in BL treatment. We identified all BL patients registered in the Polish National Cancer Registry in 1999-2017. Observed survival (OS) was evaluated deploying the life table method. Univariate and multivariate Cox proportional hazards regression models were fit to generate hazard ratios (HR) and the corresponding 95% confidence intervals (95% CI), describing the association between exposures (sex, age at the diagnosis, year of diagnosis, and region of residence) and time-to-event (death). Two-sided log-rank test was applied to assess the significance of exposures. Overall, 937 BL cases were included in the study (654 men and 283 women). Between the periods 1999-2005 and 2015-2017, the 3-year OS changed from 56.0% (95% CI 50.4 to 62.2%) to 73.8% (68.1 to 80.0%; P < 0.001), and the 5-year OS increased from 53.8% (48.2 to 60.0%) to 73.0% (67.1 to 79.3%; P < 0.001). The death HR was significantly higher in adolescents and young adults' (AYA) and adults' groups than in pediatric patients (HR = 3.00, 95% CI 2.05 to 4.39, P < 0.001, for AYA; and HR = 7.30, 5.14 to 10.3, P < 0.001, for adults). During the last two decades, the survival of Polish BL patients has been systematically improving. The death hazard ratio is most significantly associated with the patients' age at diagnosis and year of diagnosis, and not associated with sex or region of residence.