Does Vitamin D deficiency predict tumour malignancy in patient with bone tumours? Data from a multi-center cohort analysis

Abstract Vitamin D deficiency is a global health concern that is estimated to afflict over one billion people globally. The major role of vitamin D is that of a regulator of calcium and phosphate metabolism, thus, being essential for proper bone mineralisation. Concomitantly, vitamin D is known to exert numerous extra-skeletal actions. For example, it has become evident that vitamin D has direct anti-proliferative, pro-differentiation and pro-apoptotic actions on cancer cells. Hence, vitamin D deficiency has been associated with increased cancer risk and worse prognosis in several malignancies. We have recently demonstrated that vitamin D deficiency promotes secondary cancer growth in bone. These findings were partly attributable to an increase in bone remodelling but also through direct effects of vitamin D on cancer cells. To date, very little is known about vitamin D status of patients with bone tumours in general. Thus, the objective of this study was to assess vitamin D status of patients with diverse bone tumours. Moreover, the aim was to elucidate whether or not there is an association between pre-diagnostic vitamin D status and tumour malignancy in patients with bone tumours. In a multi-center analysis, 25(OH)D, PTH and calcium levels of 225 patients that presented with various bone tumours between 2017-2018 were assessed. Collectively, 76.4% of all patients had insufficient vitamin D levels with a total mean 25(OH)D level of 21.43 ng/ml. In particular, 52.0% (117/225) of patients were identified as vitamin D deficient and further 24.4% of patients (55/225) were vitamin D insufficient. Notably, patients diagnosed with malignant bone tumours had significantly lower 25(OH)D levels than patients diagnosed with benign bone tumours (19.3 vs. 22.75 ng/ml; p=0.0398). In conclusion, we found a widespread and distressing rate of vitamin D deficiency and insufficiency in patients with bone tumours. Moreover, we identified a potential association between pre-diagnostic vitamin D status and tumour malignancy in patients with bone tumours. Given the essential role of vitamin D for regular bone mineralisation, ensuring sufficient vitamin D status is of utmost importance especially for patients with bone tumours. Thus, we believe that 25(OH)D status should routinely be monitored in these patients.