The findings, published in the American Journal of Hematology, hint that the racial disparity has shrunk over time, especially within the first few years of the targeted-therapy era. Still, “Black patients had a shorter median overall survival of 7 years compared to 9 years for White patients,” study coauthor Deborah Stephens, DO, of the University of Utah Huntsman Cancer Institute, said in an interview. “Clearly, more research is needed to tease out the biologic or economic barriers to achieving prolonged survival.”
As the researchers noted, CLL is far more common among White patients (5.1 cases per 100,000) than other races (Black patients: 3.2 cases per 100,000; Hispanic patients: 2.1 cases per 100,000; Asian American patients: 1.1 per 100,000). In total, non-White patients make up just 11%-13% of CLL cases in the United States.
According to Dr. Stephens, “little is known or published” about Black patients with CLL, “and it is still a mystery why fewer patients that are Black develop CLL and why this group would have shorter survival.”
Dr. Stephens and colleagues launched the new study – the largest of its kind to date – to understand disparities between White and Black patients over most of the past 20 years. The researchers especially wanted to analyze trends during the last decade, when targeted therapies revolutionized treatment of the disease.
The study authors analyzed data in the National Cancer Database for 97,804 patients diagnosed from 2004 to 2018 (90.7% White, 7.6% Black, 0.6% Asian, 1.1% other). Of patients who reported ethnicity (n = 93,555), 2.6% were Hispanic.
Black patients were more likely to have begun CLL therapy at diagnosis (35.9%) than were White patients (23.6%), a sign that Black patients had more advanced disease. Black patients also had shorter overall survival (7.0 years, 95% confidence interval [CI], 6.7–7.3 years) vs. White patients (9.1 years, 95% CI, 9.0–9.3 years, P < .001).
“This finding could be due to underlying biologic differences in the pathology of CLL, when comparing patients across racial groups,” Dr. Stephens said. “Additionally, there could be differences in access to care. Notably, there are fewer racial minorities enrolled in clinical trials, and perhaps we are not individualizing therapy for unique biologic factors seen in CLL affecting racial minorities.”
Other factors also could be at play. Black patients were more likely than were White patients to have one or more comorbidities (27.9% vs. 21.3%, P < .001), lack insurance (6.6% vs. 2.1%, P < .001) and live in lower-income neighborhoods (47.7% vs. 13.1%, P < .001).
What explains the gap in outcomes? In an interview, study lead author Victoria Vardell, MD, of the University of Utah, Salt Lake City, noted that researchers often attribute worse medical outcomes in Black patients to economic and social disparities.
“However, when we adjusted for a number of surrogate markers of health care access, including income, comorbidities, and location, among others, this disparity remained. That indicates that this may be a more complex problem in CLL in particular. Certainly, we cannot adjust for all the socioeconomic strain placed on Black Americans, including those with CLL, but there may be molecular features related to ancestry or environmental exposures that also play a role,” Dr. Vardell said.
She added that “the high cost and difficulty obtaining many novel therapies, particularly in the clinical trial setting, places significantly higher burdens on already disadvantaged populations.”
There is some good news in the new report. “Promisingly, our data suggest that the survival disparity between White and Black patients with CLL may be improving, particularly within the last 5 years, though longer follow-up is needed to confirm significance,” the researchers reported.
Alessandra Ferrajoli, MD, of M.D. Anderson Cancer Center, Houston, who has studied racial disparities in CLL, praised the study in an interview. As she noted, it examines an impressively large population.
The explanations for the disparities are still elusive, she said, although it seems clear there are multiple factors at play. “We don’t know if the disease has the same characteristics in African-Americans as in Whites,” Dr. Ferrajoli said. However, she noted, there’s “no indication that the response to treatment is different according to race.”
Moving forward, she said, the study findings “reinforce the fact that we need to pay attention to this population and be quite attentive to their characteristics.”
No study funding was reported. The authors and Dr. Ferrajoli have no disclosures.