Poor survival and temporal trends in blastic plasmacytoid dendritic cell neoplasm: A SEER 2000–2022 analysis

Abstract Background: Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare and aggressive hematologic malignancy with evolving therapeutic options. However, population-based data on incidence and survival trends remain limited, particularly in the era of novel agents such as tagraxofusp. We aimed to assess incidence, demographic characteristics, treatment patterns, temporal survival trends, and prognostic factors using a large U.S. cancer registry. Methods: Patients diagnosed with BPDCN from 2000–2022 were identified in the SEER database using ICD-O-3 histology code 9727. Age-adjusted incidence rates (per 100,000) were calculated using SEER*Stat with the 2000 U.S. standard population. Kaplan-Meier analysis estimated overall survival (OS), and multivariable Cox regression identified prognostic factors, adjusting for age, sex, race, chemotherapy, and radiation. Temporal survival trends were analyzed using log-linear regression to estimate annual percent change... Results: A total of 658 patients were included. The age-adjusted incidence was 0.05 per 100,000, increasing significantly with age (rate ratio 5.2 in ≥75 years; p<0.001). Median age was 68 years; 69.9% were male, and 84.8% were White. Radiation and chemotherapy were reported in 15.8% and 76.6%, respectively. The most common primary site was extranodal (50.8%). Median OS was 25 months, with 1-, 3-, and 5-year OS rates of 66.8%, 45.1%, and 39.9%, respectively. On multivariable analysis, radiation was associated with increased mortality (HR 1.67; 95% CI: 1.24–2.24; p=0.001), while chemotherapy showed a nonsignificant protective trend (HR 0.80; p=0.077). Male sex predicted inferior OS (HR 1.33; p=0.014). Compared to White patients, Asian/Pacific Islanders (HR 0.21; p=0.003) and Black patients (HR 0.30; p=0.012) had improved OS. Temporal analysis revealed a 10.8% annual decline in mean survival (p<0.001). Conclusions: BPDCN predominantly affects older males and continues to carry poor survival despite high chemotherapy utilization. Worsening survival trends and limited radiation benefit underscore the need for optimized therapeutic strategies, improved data capture on novel agents, and equitable access to emerging treatments. Impact Statement: This is the first SEER-based study to comprehensively evaluate temporal survival trends, treatment patterns, and demographic disparities in BPDCN over two decades. Limitations: SEER lacks information on stem cell transplantation, novel targeted therapy use, and performance status, which may influence outcomes.