A multivariate analysis of EFS and OS (dependent variable) including the covariables age at diagnosis, sex, presence/non-presence of PTH ≥47 pg/mL and of vitamin D deficiency showed a significant association with inferior EFS in the disease groups: embryonal malignancies, lymphatic malignancies, and malignant PBT for elevated PTH only Fig. 4A–C. Here, PTH is linked to vitamin D deficiency.