Epidemiology of Aggressive NK-Cell Leukemia in the United States: A SEER Population-Based Study

Abstract

INTRODUCTION Aggressive NK-cell leukemia ( ANKL) is a systemic lymphoproliferative disorder of natural killer (NK) cells frequently associated with Epstein-Barr virus (EBV) which has been grouped under histiocytic/dendritic neoplasms in the 2008 WHO classification of hematopoietic neoplasms. Due to rarity of diagnosis, the current available literature is limited to case reports and case series. This population-based study using Surveillance Epidemiology and End result program (SEER) is the largest to explore demographic characteristics, survival patterns and long-term outcomes in patients with ANKL in the United States. MATERIALS AND METHODS We utilized SEER 18 November 2020 submission database to select all patients (> 1 years of age) diagnosed from 2000-2018 with ANKL using International Classification of Diseases for Oncology edition 3 (ICD-O-3) code of 9948/3. Patients were divided into various cohorts based on age (<60 years, 60-79 years, >80 years), sex, race (Caucasians, African American, Asian/Pacific islander and American Indians/Alaska natives) and median household income of county of residence (< $ 50,000 vs > $50,000). We used SEER*stat to calculate age adjusted incidence rate using 2000 US standard population. Kaplan Meier curve was utilized to calculate 5-year overall survival. Cox proportional hazard model was used for multivariate analysis of factors associated with survival and p<0.05 was considered significant. RESULTS A total of 140 patients were identified with ANKL. The median age at diagnosis is 58 years. The crude, age-adjusted to 2000 US standard population and age-specific incidence rate of HCD in Unites states is < 1/100, 000 respectively. The incidence in males is 1.9 times that of females- 92 males (65.7%) and 48 females (34.2%). Between 2001-2018, minimum number of cases were diagnosed in 2010 (n=2).Out of the cohort, 107 patients were White (76.4%), 21 patients were Asian or Pacific islander (15 %), 9 patients were African Americans (6.4%) and 3 patients were American Indian/Alaska native (2.1%). The median overall survival was 7 months (95% CI; 0-16). Survival rates at 1year, 2 years and 5 years were found to be 45.3% , 37.1 % and 31.1% respectively [Figure 1]. 5 year overall survival rates are as follows- Whites ( 69.7% ), Blacks ( 63.1%), American Indian (59.9%), Asian or Pacific Islander ( 66.8%). On multivariate analysis, black race was associated with poor outcomes (p 0.008), whereas sex, income and age had no significant effect on cancer outcomes. CONCLUSIONS Our study shows that ANKL is a rare hematological malignancy in general population with a poor median survival of less than one year. Males are twice more likely to be affected than females with poor outcomes in africo-americans. Figure 1 Figure 1. Disclosures No relevant conflicts of interest to declare.

Aggressive Natural Killer Cell Leukemia: A Brief Overview of Its Genomic Landscape, Histological Features, and Current Management

“…In the 2016 World Health Organization (WHO) classification, ANKL is classified as a type of "Mature T and NK neoplasm" and has an association with the Epstein-Barr Virus (EBV) [1]. Males are twice as likely as females to be diagnosed with ANKL, with an age distribution that favors older populations, except for young adult Asian males [2][3][4][5]. The median overall survival (mOS) of ANKL is seven months, with decreasing survival rates from 45% to 31% from one year to five years, respectively [5].…”

“…Males are twice as likely as females to be diagnosed with ANKL, with an age distribution that favors older populations, except for young adult Asian males [2][3][4][5]. The median overall survival (mOS) of ANKL is seven months, with decreasing survival rates from 45% to 31% from one year to five years, respectively [5]. Racial disparities exist in survival as African American patients are more likely to have poorer outcomes [5].…”

“…The median overall survival (mOS) of ANKL is seven months, with decreasing survival rates from 45% to 31% from one year to five years, respectively [ 5 ]. Racial disparities exist in survival as African American patients are more likely to have poorer outcomes [ 5 ]. Although there are currently no therapies approved by the US Food and Drug Administration (FDA) for the treatment of ANKL, advancements in the field of genomics have considerably assisted scientists in better understanding this malignancy.…”