Risk and Therapeutic Outcomes in a Multiethnic Group of Acute Lymphoblastic Leukemia Patients Treated at a Large Public Hospital

Abstract

Despite improvements in the treatment of adults with acute lymphoblastic leukemia (ALL) during the last decade, most patients will relapse and ultimately die of disease. Although some factors that affect risk of disease and treatment outcome are known, our ability to predict response and tailor treatments is far from perfect. In particular, we observed that the majority of the ALL patients treated at our large public hospital in Houston, TX were Hispanic. In order to more closely examine this trend and attempt to identify characteristics that would predict risk or therapeutic response, we performed a retrospective analysis of all patients with precursor B-cell ALL, T-cell ALL, and Burkitt lymphoma treated at our hospital over a fifteen year period. One hundred thirteen patients were identified, including sixty-one with precursor B-cell ALL, thirty-two with Burkitt lymphoma, sixteen with T-cell ALL, and four patients with additional features. All patients were treated with HyperCVAD, alternating with methoxtrexate and cytarabine, although some patients had therapeutic modifications because of disease characteristics, particularly in the first course. The median overall survival for all patients was 357 days. Patients with precursor B-cell ALL had the poorest outcome in both overall survival and progression-free survival, and a less favorable outcome than expected from the literature with a 38% two-year survival (95% CI: 54–92%). In contrast, patients with Burkitt lymphoma had an 80% 2-year survival (95% CI: 54%–92%) and those with T-cell ALL had a 63% 2-year survival (95% CI: 32%–83%). The outcomes for Burkitt lymphoma and T-cell ALL are similar to those reported in the literature. Nearly 80% of the patients with precursor B-cell ALL were Hispanic, and most were older than thirty (mean age 36.4 years) with few comorbidities. In contrast, only about 40% of the other high grade leukemia/lymphoma patients were Hispanic, reflecting more closely the racial/ethnic distribution of the population served by the hospital. While our precursor B-cell ALL patients were predominantly Hispanic, there was no statistical difference in overall survival or progression-free survival for Hispanic versus non-Hispanic patients. Hispanic patients with pre-B ALL had a 38% 2-year survival (95% CI: 20%–55%) while non- Hispanic patients had a 41% 2-year survival (95% CI: 12%–69%). Patients younger than thirty with precursor B-cell ALL had a statistically significant survival benefit compared to older patients. Fourteen patients (22.6%) with precursor B-cell ALL had a white blood cell count greater than 50,000, and these patients had significantly poorer outcomes. There was no correlation between cytogenetic abnormalities and outcome; however, very few patients were found to harbor the 9:22 translocation. There was a high incidence of CD20 positivity (55.7%) in patients with precursor B-cell ALL; however, there was no statistically significant correlation with overall survival or progression-free survival. Thus in our multiethnic patient population, patients with precursor B-cell ALL had significantly poorer outcomes than those reported in the literature, while patients with T-cell ALL or Burkitt lymphoma had outcomes to those reported in the literature using the identical chemotherapy regimen. The older age of the precursor B-cell ALL patients may have contributed to this poorer outcome. As noted above, our precursor B-cell ALL patients were predominately Hispanic as compared to the other leukemia patients we studied. Although Hispanic ethnicity did not clearly contribute to outcome, risk of developing precursor B-cell ALL appears to be greater in the Hispanic population.