Survival Outcomes in Blastic Plasmacytoid Dendritic Cell Neoplasm (2001-2012)

Background: BPDCN is a rare subtype of aggressive acute leukemia that usually has an indolent clinical presentation such as isolated solitary or multiple cutaneous lesions. Despite initial clinical responses to systemic chemotherapy, BPDCN follows an aggressive course with a reported median OS of approximately 8-14 months based on single-center studies. We aimed to determine the OS of BPDCN and its predictors utilizing a US population-based database.

Methods: Using International Classification of Disease for Oncology, 3rd edition (ICD-O-3) code 9727/3, SEER 18 database was analyzed to identify adult patients with BPDCN diagnosed from 2001-2012. We divided the entire cohort into 3 groups based on time periods of 4 years each (2001-2004, 2005-2008, 2008-2012) to represent early (E), middle (M) and late (L) cohorts. Age, sex, race, marital status, radiation use, and OS were compared across the three time periods. Multivariate analyses of OS were performed using Cox regression to adjust for significant covariates. A p-value of <0.05 was considered statistically significant.

Results: Of 417 patients, the majority were males (67%), patients aged ≤ 60 years (75%) and whites (82%). A higher proportion of patients were diagnosed in the early time period (E=43% vs. M=29% vs. L = 29%). About a sixth of the cohort (17%) received radiation therapy. Median OS was not reached for the cohort. Five-year OS was higher for patients ≤ 60 years, as compared to patients >60 years (70% vs. 50%, p<0.01). On a multivariate analysis, age >60 years (hazard ratio, HR 2.05; 95% confidence interval, CI 1.28-3.27, p <0.008) and African American ethnicity (HR 1.79; 95% CI 1.10-2.89, p=0.018) were associated with a higher hazard for death whereas OS did not differ based on sex, marital status, time period, or the use of radiation therapy. Of the 106 patients >60 years, the majority were males (68%), whites (93%), married (74%), and did not receive radiation (92%). On a multivariate analysis after adjusting for age, sex, race, time of diagnosis, and radiation therapy, being single (marital status) was associated with a worse OS (HR2.24; 95% CI 1.05-4.77, p=0.034) among patients >60 years.

Conclusions: To our knowledge, this is the largest and most recent population-based study in BPDCN. Compared to prior single-center studies, our results demonstrate much better OS. Older age and African American ethnicity are determined to be negative prognostic factors for OS. Single older patients are at even a higher risk of mortality. The study findings may help in patient counseling and informed decision-making. Racial disparities in OS require further investigation.