In some studies, the prognosis for girls with ALL is slightly better than it is for boys with ALL.[58,59,60] One reason for the better prognosis for girls is the occurrence of testicular relapses among boys, but boys also appear to be at increased risk of bone marrow and CNS relapse for reasons that are not well understood.[58,59,60] While some reports describe outcomes for boys as closely approaching those of girls,[43,61] larger clinical trial experiences and national data continue to show somewhat lower survival rates for boys.[22,23,62]
Survival rates in black and Hispanic children with ALL have been somewhat lower than the rates in white children with ALL.[63,64] Asian children with ALL fare slightly better than white children.
The reason for better outcomes in white and Asian children than in black and Hispanic children is at least partially explained by the different spectrum of ALL subtypes. For example, black children have a higher relative incidence of T-cell ALL and lower rates of favorable genetic subtypes of precursor B-cell ALL. Differences in outcome may also be related to treatment adherence, as illustrated by a study of adherence to oral 6-mercaptopurine in maintenance therapy. In this study, there was an increased risk of relapse in Hispanic children compared with non-Hispanic white children, depending on the level of adherence, even when adjusting for other known variables. However, at adherence rates of 90% or more, Hispanic children continued to demonstrate increased rates of relapse. Ancestry-related genomic variations may also contribute to racial/ethnic disparities in both the incidence and outcome of ALL. For example, the differential presence of specific host polymorphisms in different racial/ethnic groups may contribute to outcome disparities, as illustrated by the occurrence of single nucleotide polymorphisms in the ARID5B gene that occur more frequently among Hispanics and are linked to both ALL susceptibility and to relapse hazard.
Leukemic cell characteristics affecting prognosis
Leukemic cell characteristics affecting prognosis include the following:
- Cytogenetics/genomic alterations.