Abstract: Objective In 2022, an estimated 81,900 new cases of leukemia were reported  in China, ranking 12th among domestic malignant tumors. The epidemiological characteristics of leukemia are influenced by regional environment and the distribution of medical resources. This study analyzes the trends in leukemia incidence within the cancer registration areas of Gansu Province from 2010 to 2021 and projects the incidence rates from 2022 to 2030. Methods Based on leukemia incidence data from 15 cancer registries in Gansu Province between 2010 and 2021, incidence rates were calculated by age, sex, and urban⁃rural distribution. The age⁃standardized incidence rate by Chinese standard population (ASIRC) was calculated using the 2000 Chinese standard population structure. The Joinpoint regression model was used to analyze incidence trends, calculating the annual percentage change (APC), average annual percentage change (AAPC), and their 95% confidence interval (CI). The Bayesian age⁃period⁃cohort (BAPC) model was applied to predict leukemia incidence in Gansu Province from 2022 to 2030. Results From 2010 to 2021, the overall ASIRC in Gansu Province showed a non‑significant downward trend (AAPC = −4.58%, 95%CI: −9.04% to 0.09%, P=0.055), with a significant decline observed from 2019 to 2021 (APC = −26.11%, P=0.014). The ASIRC level was higher in male than in female, but neither showed a statistically significant downward trend (all P>0.05). No significant change was found in urban areas (AAPC=0.24%, 95%CI: −5.62% to 6.46%, P=0.939), while rural areas exhibited a significant downward trend (AAPC=−7.76%, 95%CI: −14.04% to −1.03%, P=0.025). From 2010 to 2021 in Gansu Province, the ASIRC change of leukemia in the 0-29 and 40-49 age groups decreased at average annual rates of 5.09% and 1.89%, respectively. The results of birth cohort analysis showed that the ASIRC of leukemia in the early birth cohort was at a high level particularly among individuals aged over 70 years. Successive birth cohorts showed declining ASIRC for aged 0-49 years, while those aged ≥50 years demonstrated fluctuating upward trend. The BAPC model predicted that the ASIRC of leukemia for the overall population, male, urban areas, and rural areas would decline from 2.60/105, 3.00/105, 2.73/105, and 2.51/105 in 2021 to 0.93/105, 1.28/105, 0.93/105, and 2.17/105 in 2030, respectively. In contrast, the ASIRC for female would increase from 2.18/105 in 2021 to 2.94/105 in 2030. Conclusions From 2010 to 2021, the ASIRC of leukemia in Gansu Province declined overall, with a particularly noticeable decrease in rural areas. The ASIRC in the 0-49 age group showed a declining trend, while it fluctuates upward after the age 50. The ASIRC of leukemia further declines by 2030, suggesting that prevention and control measures have achieved results. However, continued efforts are needed to strengthen interventions for high⁃risk groups and maintain long⁃term surveillance.

Key words: Leukemia, Incidence trend, Prediction, Bayesian age?period?cohort model, Gansu Province