Background: Ethnic differences in the survival of children treated for acute lymphoid leukemia (ALL) have been described in several locations. Children of African, Polynesian, Native American, and Mexican ancestry had a less favorable outcome than children of European ancestry when treated in a similar manner by the same physicians and nurses.
Methods: We reviewed the medical records of the 94 European-American (E-A) and 84 Mexican-American (M-A) Texas children registered and treated in national collaborative ALL therapy trials at the M. D. Anderson Cancer Center in Houston between 1974 and 1985 and followed through June 1994. Information was collected regarding age, sex, presenting clinical features, risk for relapse grouping, protocol assignment, event free survival, and the financial status of their families. Cure was defined as initial continuous complete remission for more than seven years and cessation of therapy for more than four years. Presenting characteristics of E-A and M-A children were compared, and then related to cure rates by univariate and multivariate analyses. Event free survival rates of E-A and M-A children were determined together and by sex.
Results: Comparing presenting features, financial status as identified by pay code was significantly less for M-A children. Other features were not significantly different. By univariate analysis, an age of 2 to 6 years, female sex, initial white blood cell count below 10,000/microL, low risk grouping, registration on the most recent protocol, and full pay status were significantly associated with higher cure rates. By multivariate analysis, male gender, high risk group, and registration on earlier protocols were found to be significantly associated with a low cure rate. Event free survival and cure rate were lower for M-A children, but the differences were not statistically significant.
Conclusions: Further study of larger numbers of patients, including contemporary immunophenotypic and genotypic characterization of ALL, is needed for better definition of possible ethnic differences. Ethnicity and financial status should be included in the analysis of clinical trials of ALL therapy.