METHODS
This was an international, multicentric retrospective cohort study. Ten
Latin-American oncologic centers providing care to children and
adolescents with LLy participated, collecting and recording the clinical
data of their patients. As a retrospective study of de-identified
secondary use of clinical data the St. Jude IRB determined an exempt
research status, and this determination was provided to the site
principal investigator for local study submission and approval at each
one of the participating institutions.
Study inclusion criteria were a diagnosis of LLy of any
phenotype between January 1, 2007 and December 31, 2017; age less than
19 years; and clinical medical records available for review and
abstraction. For each patient variables collected included age, gender,
lymphoma immunophenotype, stage and sites of disease, treatment regimen
administered and clinical status. Data was collected in a case report
form and then transcribed to an electronic password-secure REDCap
database. Study staff at St. Jude periodically reviewed the data entered
and queried sites for missing data or for clarifications. Online
meetings were held for training, progress evaluation and other
discussions.
Statistical analysis
Event-free survival (EFS) was calculated from the time of diagnosis
until death, relapse, progression, abandonment or the occurrence of a
second malignancy. Patients with no events were censored at the date of
last follow-up. Overall survival (OS) was defined as time from diagnosis
to death or date of last follow-up for those who were still alive. The
EFS and overall survival (OS) were calculated using the Kaplan–Meier
method, and groups were compared using a log-rank test. Induction deaths
were defined as those occurring in the first 30 days after admission,
before remission evaluation. Deaths in complete remission included those
attributed to any cause other than LLy after achieving a complete
remission. Abandonment was defined as failure to adhere to scheduled or
unscheduled visits during therapy for at least four consecutive weeks.
Follow-up was updated as of March 1, 2020, thus each patient had at
least 3 years of follow-up.
Categorical data are expressed in absolute frequencies and percentages.
Continuous variables are expressed as medians (range). The
χ2 or Fisher exact test was used for the analysis of
categorical variables and Mann-Whitney test for continuous variables.