Racial differences in presentation, referral and treatment patterns and survival in adult patients with acute myeloid leukemia: A single-institution experience
Introduction
Acute myeloid leukemia (AML) is characterized by maturation arrest of a malignant clone of myeloid cells, with inhibition of normal hematopoiesis. AML is the common type of acute leukemia affecting adults, and its incidence increases with age. The age-adjusted incidence rate of AML in the United States is 3.5 per 100,000 people per year. AML is more common in males, with a male to female ratio of 1.48, and is also more common in whites, with a white to black ratio of 1.2 [1].
Racial differences in clinical characteristics and outcome have been identified in a number of cancers, with blacks often having shorter overall survival (OS) than whites. This relationship has been identified in head and neck [2], [3], [4], skin [5], esophageal [6], colon [7], prostate [8], [9], [10], ovarian [10] and breast cancers [10], [11]. The observed differences between populations are likely multifactorial, reflecting differences in access to care due to socioeconomic disparities, environmental exposures, cultural differences, tumor biology, and genetic mutations or polymorphisms influencing response to and/or toxicity of chemotherapeutic agents [12]. Socioeconomic disparities are generally thought to be the most important of these determinants and indeed many observed racial disparities are at least mitigated when these factors are taken into account.
Racial differences in disease presentation and treatment outcome have not been extensively studied in adult AML. Karyotype is the most significant predictor of outcome in AML, but only limited information is available on the distribution of AML karyotypes across races [13]. Additionally, molecular abnormalities with prognostic significance, most notably mutations of fms-like tyrosine kinase receptor-3 (FLT3), have been identified as having strong prognostic significance in AML [14], but there is little information available about their incidence in different races. Finally, data on outcomes by race are limited and inconsistent [10], [13], [15], [16].
To assess racial differences in pretreatment characteristics, referral and treatment patterns and outcome in adult AML, we studied patients evaluated and treated from 2000 through 2009 at the University of Maryland Greenebaum Cancer Center (UMGCC) in Baltimore, Maryland, a tertiary care referral center with a relatively high proportion of minority patients.
Section snippets
Study population
We conducted a retrospective study of all patients with a diagnosis of AML evaluated at UMGCC from January 1, 2000 through December 31, 2009. This study was approved by the University of Maryland School of Medicine Institutional Review Board.
Data collection
Data were obtained from retrospective electronic and paper chart review. Information collected included diagnosis date, date of referral to UMGCC, self-reported race, gender, date of birth, zip code of residence, presence or absence of an antecedent
Results
A total of 548 patients with a diagnosis of AML were identified, of whom 399 (73%) were white, 105 (19%) black, 22 (4%) Hispanic and 22 (4%) Asian. Karyotype data were available for 510 (94%) and FLT3 data for 177 (32%), with availability of karyotype and FLT3 data similar for all races. As the vast majority of our population was white or black, comparisons were limited to differences between these two groups.
Time from AML diagnosis to referral to UMGCC did not differ in blacks and whites (p =
Discussion
In this study in a single institution with a 19% black AML population, we found that black adult AML patients were younger, were more commonly female and had a higher incidence of complex karyotypes as well as a lower incidence of normal karyotypes, but had similar survival when compared to whites. FLT3 mutations were equally frequent in black and white patients, but were a stronger predictor of OS in blacks than in whites with intermediate-risk karyotypes. To our knowledge, our study
Conflict of interest
There are no conflicts of interest to disclose.
Acknowledgements
Contributions: JB was the principal investigator and takes primary responsibility for the paper. YN was responsible for collection of cytogenic data. JB, AD, IG, MT, MB wrote the paper. JB performed data collection and analysis. IG, MT, MB assisted with data collection and AD assisted with statistical analysis. All authors had final approval of the manuscript.
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