Ethnic Disparities in Chronic Lymphocytic Leukemia Survival: A SEER Database Review

Abstract

757 Background: Chronic lymphocytic leukemia (CLL) is the most common leukemia seen in adults. Previous population-based research in CLL has not represented the current ethnic makeup and diversity within the US population. We undertook a large Surveillance Epidemiology and End Results (SEER) based analysis to assess disparities in outcome among different ethnic subgroups of CLL patients, so that therapeutic resources can be utilized effectively. Methods: The SEER-18 Registry (1973–2009) was used to retrieve a population of 60,293 patients with established diagnosis of CLL (Histology code: 9823). The cohort was restricted to adults (>18 yrs) diagnosed after January 1, 1992, since ethnic minorities were underrepresented in SEER prior to that. Cases reported in death certificate/autopsy, those without a confirmatory diagnosis, those with ethnicity recorded as unknown/other or those that did not have follow up post diagnosis were excluded. Using Cox proportional hazards models, adjusted for confounding variables, association between patient characteristics and survival (overall; OS and CLL-specific; CLLSS) was evaluated. Analysis was performed utilizing the SAS software (v9.2). All statistical tests were two-sided with a significance level of 5%. Results: A total of 37,834 patients (22,581 males; 60%, 15,253 females; 40%) were included in the final analysis. Age group (yr) cohorts included: 18–44 (861; 2%) 45–54 (3,587; 9%), 55–64 (7,684; 20%), 65–74 (10,966; 29%), and ≥75 (14,736; 39%). For survival trends over time, stratification by year of diagnosis was used: 1992–1999 (9,837; 26%), 2000–2004 (14,129; 37%), 2005–2009 (13,868; 37%). Stratification by race/ethnicity included: White (32,980; 87%), African-American (AA: 2,486; 7%), Hispanic (1,536; 4%), Asian (737; 2%), and Native American (NA: 95; 0.25%). Median age ranged from 68 yr (AA and Asian) to 71 yr (Whites) (Figure 1). For survival analysis, NA ethnic group was excluded due to their small numbers. Females had a significantly better median OS (8.3 yr vs. 6.4 yr; p<0.001) as well as CLLSS (p<0.001) than males, when evaluated for the whole population and across different age groups. Both, OS and CLLSS progressively and significantly (p<0.001) declined with advancing age. Progressive significant improvement was seen in OS over time across cohorts by year of diagnosis (6.3 yr, 7.3 yr, 7.4 yr; p<0.001). This improvement in OS persisted over time for age groups <75 yr, but for ≥75 yr, the improvement was lost in the most recent time period cohort (2005–2009). The percentage of patients dying of CLL has decreased progressively over time suggesting an improvement in therapy. Among various ethnicities, Asians had the best (7.5 yr) and AA had the worst (4.8 yr) OS (p=0.006) (Figure 2) and CLLSS (p<0.001). In a multivariate model, AA continued to have the worst OS across all age groups (p<0.001), while Whites had the best OS in age groups <75 yr and Asians had the best among patients ≥75 yrs. Percentage of patients dying from CLL was highest in AA across age groups, but lowest for Whites in age groups <75 yr, while in Hispanics in patients ≥75 yr. Trends in CLLSS were noted to be more heterogeneous among ethnicities than trends in OS. Conclusions: This report presents the largest population-based analysis of patient characteristics including ethnicity and survival in CLL in the era of novel therapeutic agents. Older patients had worse OS among all ethnic subgroups. Progressive improvement in CLLSS was noted over time suggesting a possible impact of new therapeutics, however this was not seen in ≥75 yr patients. AA patients had the worst OS among all ethnicities and age groups. This survival difference was most significant and pronounced in younger patients, which has important implications. For example, this survival disadvantage may represent poor access to optimal healthcare warranting development of new initiatives directed towards this ethnic minority. On the other hand discrete biological variants may underlie the more aggressive disease biology in younger AA patients underscoring the need to further investigate and delineate the molecular biology of CLL in ethnic minorities. Studies of outcome disparities are important not only for evaluating disease characteristics but also management needs of specific patient populations and are critical for designing programs to deliver optimal healthcare to ethnically diverse populations. Disclosures: No relevant conflicts of interest to declare.

Gender differences in leukemia outcomes based on health care expenditures using estimates from the GLOBOCAN 2020

“…Notably, gender variations have a significant impact on cancer, resulting in incidence rates being up to 20% greater and mortality rates up to 40% higher among males [ 14 ]. A collection of previous studies has clarified that the notable difference between sexes is related to many factors, namely awareness, treatment, healthcare use, disease control rate, time of diagnosis, occupational exposure, and differences in overall survival [ 15 – 17 ]. In terms of leukemia, the male population exhibited higher rates of incidence and mortality compared to females, highlighting the impact of biologic and epidemiologic factors [ 1 , 4 , 10 , 11 , 18 , 19 ].…”

Influence of Racial and Ethnic Identity on Overall Survival in Patients with Chronic Lymphocytic Leukemia

“…(1,2) This amounts to a low prevalence of CLL in non-White populations, who represent between 11-13% of CLL patients. (3,4) While the etiology underlying the decreased incidence of CLL in racial and ethnic minority populations is not fully understood, it is hypothesized to be related to genetic rather than environmental factors. (5)(6)(7)(8) Due to low incidence of CLL in non-White persons, there are minimal data available to help understand how the disease course of CLL may differ between racial and ethnic groups.…”

“…Furthermore, population and multi-institution studies have raised concerns that racial and ethnic minority patients with CLL have inferior survival as compared to White patients. (3,(9)(10)(11)(12)(13) The largest study to date used the SEER database to identify 2 059 Black patients from a total population of 30 622 CLL patients, diagnosed between 1992-2007. In this study, Black patients presented with CLL at a younger age than White patients (mean 67 years vs 70 years) and had significantly lower rates of 5-year relative survival than White patients, at 63.9 vs 77.1%, respectively.…”

Influence of racial and ethnic identity on overall survival in patients with chronic lymphocytic leukemia

“…Furthermore, population and multi-institution studies have raised concerns that racial and ethnic minority patients with CLL have inferior survival as compared to White patients. [1][2][3][4][5] However, since these studies were published, the management of CLL has dramatically improved. With the approval of Ibrutinib, the first-in-class Bruton's tyrosine kinase inhibitor, in 2014, the treatment landscape has shifted to predominately novel targeted therapies.…”