Statistical analysis
The survival rate was estimated using the Kaplan–Meier method. An event
was defined as progression of disease, toxic death, or secondary cancer.
In addition, prognostic factors were assessed using univariate and
multivariate Cox proportional hazard regression models. Prognostic
factors assessed using univariate analysis were age, INSS stage, bone
metastasis, bone marrow metastasis, liver metastasis,
MSI15, MYCN amplification, INPC pathology, INRC
before HDC, radiation, surgery before HDC, retinoic acid, and tandem
SCT. Factors showing significant adverse effects on event-free survival
(EFS) in a log-rank test were assessed using a multivariable model. All
statistical analyses were performed using the R package version 3.3.3.