Vitamin D deficiency is frequent and selenium deficiency is rare in newly diagnosed breast cancer patients

Abstract Purpose:In recent years, controversial discussions increased whether vitamin D and selenium have an influence on cancer. In the present study, we examined serum vitamin D and selenium levels in breast cancer patients and potential influencing factors. Methods:110 non-metastatic breast cancer patients were included in the prospective observational “BEGYN” study at Saarland University Medical Center between September 2019 and January 2021. Clinicopathological characteristics were documented. At the baseline visit prior to therapy initiation serum vitamin D and selenium levels were measured and patients received a questionnaire on sun exposure, nutrition, and supplement use.Results:Median vitamin D value was 24 µg/l, and median selenium level was 81 µg/l. Vitamin D levels were higher among the 17 patients that reported the use of vitamin D substitution (43 µg/l versus 22 µg/l; p<0.001). In the univariate analysis, vitamin D levels were higher in summer compared to spring (p=0.004), autumn (p=0.028) and winter (p<0.001). Patients with triple negative carcinomas had a higher vitamin D level (+8,9 µg/l compared to other sub entities, p=0.035). The consumption of cream, gouda, and butter was associated with slightly lower vitamin D levels (regression coefficient: -0.36; p=0.004). Vitamin D and selenium levels are comparable to the healthy German population.Conclusion:Almost 2/3 of all breast cancer patients suffer from vitamin D deficiency at diagnosis, whereas selenium levels were in normal range in 96.2 % of the patients. Vitamin D should be measured routinely, to prevent side effects of vitamin D deficiency.