Epidemiology and Survival Outcomes in Blastic Plasmacytoid Dendritic Cell Neoplasm (BPDCN): A US Population-Based Study

Background:

Blastic plasmacytoid dendritic cell neoplasm (BPDCN) is a rare, clinically aggressive hematological malignancy arising from plasmacytoid dendritic cell precursors. BPDCN remains poorly understood due to its rarity, constantly changing nomenclature, and defining criteria. This study using the Surveillance, Epidemiology, and End Results Program (SEER) database is the largest and most recent population-based study in BPDCN. We aimed to determine the incidence, clinical characteristics, overall survival, and prognostic factors in BPDCN.

Methods:

Patients diagnosed with BPDCN from 2000-2019 were identified from the SEER 17 database using the International Classification of Disease for Oncology, 3^rd edition (ICD-O-3) code 9727. Patient characteristics, treatment, and survival information were obtained. Age-adjusted incidence rate per 100,000 population and incidence rate ratio (IRR) were calculated using SEER stat software with the year 2000 US population as the reference standard. Overall survival and prognostic factors were evaluated based on univariate survival analysis using Kaplan-Meier plot with log-rank test, and Cox proportional hazard regression model for multivariate survival analysis. All statistical analyses were conducted with a two-sided significant p value of <0.05 using SEER stat software and STATA software version 15.1.

Results:

A total of 844 patients with BPDCN were included in the study. The median age at diagnosis was 40 (IQR: 15-68) with majority < 20 years (32.5%) or > 60 years (34.3%) . Majority were males (68.1%) and Caucasians (83.5%). The lymph node was the most common primary site of involvement (56.6%) followed by the bone marrow (19.1%) and skin (13%). . Eighteen percent of the cohort received radiation therapy and 83.6% received chemotherapy. The overall incidence of BPDCN was found to be 0.05 cases per 100,000 population. Incidence was significantly lower in females than males (IRR 0.62, p < 0.01) and in African Americans compared to Caucasians (IRR 0.70m, p<0.01). There was no significant change in disease incidence from 2005 to 2019. Survival rates at 1 year, 2 years and 5 years were found to be 70%, 56% and 41% respectively. On univariate analysis, age > 60 years (p <0.01) and male gender (p< 0.01) was associated with significantly worse overall survival while survival did not differ by race (p=0.10). On multivariate analysis after adjusting for age, sex, race, marital status, radiation therapy, chemotherapy and disease primary site, age > 60 years (HR 2.70; 95% CI 2.01-3.54, p<0.01) and African American race (HR 1.44; 95% CI 1.01-2.04, p<0.04) was associated with worse overall survival.

Conclusion:

To our knowledge, this is the largest and most recent population-based study in BPDCN. Our study revealed a population level incidence of 0.05 cases per 100,000 population. Majority are Caucasian males with bimodal age distribution (<20 years and above 60 years). The lymph nodes are the most common site of involvement. Older age and African American ethnicity are negative prognostic factors for overall survival. Racial disparities in OS warrant further prognosis. More prospective studies are needed to determine disease characteristics and optimal treatment approaches for this rare life-threatening hematological malignancy.