Study shows African-American chronic lymphocytic leukemia patients don’t survive as long as others who receive similar treatment
UT MD Anderson, Duke researchers find blacks are treated quicker, have more advanced diseaseMD Anderson News Release 07/11/13
African-Americans with chronic lymphocytic leukemia who receive standard treatments respond initially as well as non-African-Americans, yet do not survive as long, researchers report in a paper published online this week in CANCER, a journal of the American Cancer Society.
“These findings suggest that standard treatments induce high response rates for African-Americans, but they don’t overcome racial differences that affect survival of CLL patients,” said the paper’s senior author, Alessandra Ferrajoli, M.D., associate professor of leukemia at The University of Texas MD Anderson Cancer Center.
“Such diverse outcomes among patients receiving similar treatment points to differences in the nature of the disease in African-Americans,” Ferrajoli said.
The study compared demographic, clinical, treatment and outcome data from 84 African-Americans and 1,571 non-African-Americans referred to MD Anderson and Duke University Medical Center between 1997 and 2011.
They found that African-Americans have more advanced disease upon referral, reflected in higher rates of 10 disease factors associated with poor prognosis. These include a variety of genetic alterations and protein levels as well as earlier CLL symptoms.
Standard therapies, divergent results
The team then analyzed the records of those who required treatment over the course of the study, 43 African-Americans and 607 non-African-American patients who received the same treatments. They found African-Americans:
- Are treated sooner, with median time to treatment after diagnosis of 14.3 months vs. 57.2 months for non-blacks;
- Respond similarly to standard combinations of chemotherapy and immunotherapy, with 85 percent having at least partial responses and 56 percent having complete responses, compared with 94 percent and 58 percent respectively for non-African-Americans,
- Survive for 36 months without their disease progressing, compared with 61 months for non-black patients.
- Have a median overall survival of 152 months, while other patients’ median survival was so long that it had not been reached yet by the time the data were analyzed.
A multivariable statistical analysis showed that race had an independent negative effect on overall survival even taking into account all other demographic, clinical and treatment variables.
Earlier time to treatment reflects the more advanced nature of CLL in African-Americans upon referral, Ferrajoli said. However, the underlying cause or causes of higher rates of poor-prognosis factors that make African-Americans’ CLL so advanced are unknown, Ferrajoli said.
Research collaborations are under way that look at leukemia genomics and other characteristics to discover the biological basis behind the short response to treatment and worse survival, Ferrajoli said.
These studies are led by co-author Mark Lanasa, M.D., Ph.D., Duke’s principal investigator on the project and an assistant professor of medicine at Duke University Medical Center.
“Our findings suggest that biologic differences between CLL in African-Americans and Caucasians may account for the observed differences in patient outcomes,” Lanasa said. “This raises the questions of whether CLL in African-Americans is a biologically distinct entity or if African-American patients are more likely to develop aggressive CLL that is otherwise similar to Caucasian CLL. These types of studies are ongoing.”
Study digs deeper to understand disparities
Previous studies indicated that African-Americans have more advanced disease and shorter survival, but the MD Anderson-Duke retrospective study included detailed treatment information.
Study of racial disparities can be complicated by differences in access to high-quality care and by longer times to diagnosis. Ferrajoli and colleagues found that African-Americans in the study were referred to Duke or MD Anderson more quickly after diagnosis (2.3 months) than others (4.1 months).
“Although the observations of racial differences in cancer outcomes, including CLL, unfortunately are not new, the demonstration that these differences in survival persist even when similar therapies are administered is a novel finding and it suggests that African-American patients may have different disease biology than non-black patients,” authors of an accompanying commentary wrote.
Although shorter time from diagnosis to referral makes treatment delay an unlikely cause of the poorer prognosis of African-American patients in this study, diagnosis delays before referral could have occurred, the commentary notes.
Commentary co-authors Christopher Flowers, M.D., of the Winship Cancer Institute at Emory University, and Barbara Pro, M.D., of the Kimmel Cancer Center at Thomas Jefferson University, also note: “Future studies in CLL can use this work as a cornerstone for investigating racial disparities in this disease.”
Potential limits of their study, Ferrajoli and colleagues note, are a younger earlier median age, 59, at time of referral for both groups compared to median age of 72 for CLL patients in a national registry. This indicates a higher proportion of study patients might have had more aggressive disease.
Because the majority of study patients had Medicare or adequate private insurance, their findings might not apply to the uninsured and under-insured populations, the authors noted.
Co-authors with Ferrajoli and Lanasa are first author Lorenzo Falchi, M.D., and William Wierda of MD Anderson’s Department of Leukemia; Xuemei Wang, Ph.D., of the Department of Biostatistics; Sara Strom, Ph.D., of the Department of Epidemiology; and Catherine Coombs, M.D., of Duke University Medical Center Department of Medicine.
There was no specific funding source for this study.