Vitamin D: A complementary nutritional therapy for treatment of glioblastoma?

Glioblastoma accounts for approximately 50% of all brain tumours in adults and is considered incurable due to its heterogeneity and complex pathogenesis.1 Despite advancement of modern therapies against glioblastoma, it remains a deadly disease with poor prognosis and significantly impacts on quality of life throughout the disease course.2 Median patient survival rates range between 14-16 months following diagnosis, and a five-year survival rate of 9.8% in patients,1 resulting in a critical public health issue. Indeed, treatment of glioblastoma Vitamin D: A complementary nutritional therapy for treatment of glioblastoma? remains the most challenging task in clinical oncology.

Current therapeutic management involves maximal surgical resection of the tumour along with radiation and concomitant adjuvant temozolomide (TMZ) therapy.3 However, glioblastoma has a poor response to current conventional chemotherapeutics due to varying side effects along with a relatively short half-life of TMZ-based chemotherapy (1.8 hours).1 1,25-Dihydroxyvitamin D3 has emerged as a target of interest to be co-administered with different brain cancer treatments due its anti-proliferative and prodifferentiation effects in the CNS, including gliomas, and ability to cross the blood-brain barrier.4-6 Indeed, early studies conducted on rat glioma demonstrated that such cells respond to 1,25-dihydroxyvitamin D3.7 Thus, there are long-standing academic and patient specific interests in vitamin D supplementation as a possible concomitant therapy to counteract tumour growth or reduce cancer risk.