Vitamins, Dex and GBM

Background. The Stupp protocol is the standard of care for GBM. We explore the impacts of vitamin supplements and Dexamethasone dosages on GBM patient outcomes.
Methods. We screened electronic medical records to identify 173 GBM patients whose tumors met the 2021 WHO criteria and who received standard of care. 99 patients were Stupp protocol compliant, finishing 6-cycles of adjuvant temozolomide; 74 failed the protocol by receiving <6-cycles.
Results. Vitamin D supplements are a powerful therapeutic treatment adjunct for GBM patients and markedly improve progression free survival (PFS) and overall survival (OS). There is an inverse relationship between vitamin D supplementation and Dexamethasone usage. Vitamin D supplements increase PFS and OS, p<0.0001, and facilitate lower Dexamethasone dosages, p<0.0001. In addition, Stupp-compliance is 50% higher in patients taking vitamin D, p<0.001, independent of socioeconomic status. Vitamin D supplements also improve outcomes in those aged 61 or older, who in many studies have worse outcomes.
Dexamethasone usage shows a dose dependent negative impact on patient outcome at key steps in treatment. We find that using <1.2 mg/m2 Dexamethasone in the final week of chemoradiotherapy improves both PFS and OS. In addition, patients under this threshold were ≈50% more likely to become Stupp-compliant, p<0.003. If Dexamethasone levels are <1.2 mg/m2 at the start of adjuvant temozolomide chemotherapy, Stupp-compliance doubles, p<0.0001, and patients enjoy a two-fold improvement in OS, p<0.0001.
Conclusions. The use of Vitamin D supplementation allows for lower Dexamethasone dosage and is associated with significant improvement in PFS and OS.