The role of radiation therapy for testicular involvement is unclear. A study from St. Jude Children's Research Hospital (SJCRH) suggests that a good outcome can be achieved with aggressive conventional chemotherapy without radiation. The COG has also adopted this strategy for boys with testicular involvement that resolves completely by the end of induction therapy. The COG considers patients with testicular involvement to be high risk regardless of other presenting features, but most other large clinical trial groups in the United States and Europe do not consider testicular disease to be a high-risk feature.
Down syndrome (trisomy 21)
Outcome in children with Down syndrome and ALL has generally been reported as somewhat inferior to outcomes observed in children who do not have Down syndrome.[40,41,42,43]
The lower event-free survival (EFS) and OS of children with Down syndrome appear to be related to higher rates of treatment-related mortality and the absence of favorable biological features.[40,41,42,43,44] Patients with Down syndrome and ALL have a significantly lower incidence of favorable cytogenetic abnormalities such as ETV6-RUNX1 or trisomies of chromosomes 4 and 10.
In a report from the COG, among B-precursor ALL patients who lacked MLL translocations, BCR-ABL1, ETV6-RUNX1, or trisomies of chromosomes 4 and 10, the EFS and OS were similar in children with and without Down syndrome.
In some studies, the prognosis for girls with ALL is slightly better than it is for boys with ALL.[45,46,47] 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.[45,46,47] However, in clinical trials with high 5-year EFS rates (>80%), outcomes for boys are closely approaching those of girls.[34,48]
Survival rates in black and Hispanic children with ALL have been somewhat lower than the rates in white children with ALL.[49,50] This difference may be therapy-dependent; a report from SJCRH found no difference in outcome by racial groups.
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, blacks have a higher incidence of T-cell ALL and lower rates of favorable genetic subtypes of ALL. However, these differences do not completely explain the observed racial differences in outcome.
Leukemic cell characteristics affecting prognosis
Leukemic cell characteristics affecting prognosis include the following:
In the past, ALL lymphoblasts were classified using the French-American-British (FAB) criteria as having L1 morphology, L2 morphology, or L3 morphology. However, because of the lack of independent prognostic significance and the subjective nature of this classification system, it is no longer used.