Patients
We retrospectively reviewed the medical records of 41 newly diagnosed high-risk neuroblastoma patients who underwent HDC with a double-conditioning regimen comprising thiotepa and melphalan with auto-SCT between June 2002 and October 2012 at the National Center for Child Health and Development, Tokyo, Japan; the Osaka City General Hospital, Osaka, Japan; and the Osaka University Hospital, Osaka, Japan. This cohort included 19 patients reported in previous studies.9,11,12 The diagnosis of high-risk neuroblastoma was made on the basis of histological evaluation of tumor samples showing the presence of elevated urine vanillylmandelic acid and homovanillic acid. High-risk neuroblastoma was defined as follows:MYCN -amplified stage 2, 3, 4S, or 4 in patients of any age orMYCN -non-amplified stage 4 diagnosed at age >18 months.13 Staging was performed according to the International Neuroblastoma Staging System (INSS).14The metastatic site index (MSI), a score based on the number of metastatic systems/compartments involved, was also calculated.15