National trends in acute lymphocytic leukemia (ALL) incidence (1999–2021): A longitudinal outcome study using joinpoint analysis of age, sex, and regional disparities

Abstract INTRODUCTION Acute Lymphocytic Leukemia (ALL) is a highly aggressive hematological malignancy characterized by rapid proliferation of lymphoid progenitor cells, requiring prompt diagnosis and intensive treatment to achieve optimal outcomes. This study systematically investigates the incidence trends from 1999 to 2021, with a particular focus on demographic and regional disparities. Method: The data for this study were sourced from the Centers for Disease Control and Prevention (CDC) Wonder Database. This dataset includes the incidence rates of ALL across various age groups: under 1 year, 5-9 years, 10-14 years, 15-19 years, 20-24 years, 25-29 years, 30-34 years, 35-39 years, 40-44 years, 45-49 years, 50-54 years, 55-59 years, 60-64 years, 65-69 years, 70-74 years, 75-79 years, 80-84 years, and 85 years and older. Each year's incidence rates are expressed per 100,000 population. To determine the percentage increase, the incidence rates from 1999 were compared with those from 2021. Joinpoint regression was used to estimate average annual percent change (AAPC) with 95% confidence intervals. RESULTS From 1999 to 2021, there were 111133 reported cases of ALL. Throughout this period, the overall incidence rate showed an increase by 34.75% over two decades. This corresponds to an AAPC of 0.9073 with a 95%CI of 0.7191 (1.0958 - 10.0618) and P value < 0.000001. When examining the data by gender, men experienced lower incidence rates than women, with an incidence rate of 33.196% for men and 36.82% for women. The AAPC for women was 1.0002 with 95% CI (0.7672 - 1.2338 ), while for men, it was 0.9681 with 95% CI (0.7562 -1.1805). When looking at racial groups, Blacks or African Americans showed the greatest increase in incidence rates with AAPC of 0.8035 with 95% CI of (0.3479 - 1.2612) followed by Asian or Pacific Islanders with an AAPC of 0.7639 with 95% CI (0.2581 -1.2723), compared to other races, When it comes to regions, Southern USA had the highest incidence rate with an AAPC of 1.1902 95% CI (0.9556 - 1.4255). Age-specific trends revealed that the 1-4 year age group saw the largest relative increase in incidence, surging by 26972 with a crude incidence rate of 7.47, with the sharpest decline in later age groups until 55-59. Surprisingly, after 55-59, it started rising again from age groups 60-64 until 80-84. After age 85, however, the incidence rates started decreasing once again. CONCLUSION Incidence of ALL in children is obvious, but it has also significantly increased across the U.S. adult population, particularly after 59, with disparities most pronounced by sex, race/ethnicity & region. Targeted interventions are needed to address disparities and mitigate rising incidence rates.