Objectives: This study aimed to determine whether vitamin D levels differ between cancer patients and non-cancer control groups, to determine the differences between the reference values and also to determine the prevalence of vitamin D deficiency in cancer patients. Methods: Vitamin D levels were examined retrospectively between 2017-2018 in outpatient oncology patients and non-oncology patients who applied to Mardin State Hospital. Results: A total of 355 patients were examined (157 oncologic patient group and 198 in the control group). The median age of the oncologic patient group was 55.24 (19-85) and the control group was 55.45 (18-89). The median vitamin D value of the oncology patients was 8.15 ng / mL (?4.2-33.72) and the control group was 14.39 ng / mL (?4.2-60.13). It was statistically significant that vitamin D levels were lower in the oncology patients when compared with the control group (p<0.001). Conclusion: In this study, vitamin D deficiency was found to be very common in cancer patients (87.3% according to reference value of 20 ng/mL) and vitamin D levels were lower in cancer patients compared to the control group. 10 ng/ mL is a suitable reference value for defining vitamin D deficiency in cancer patients. Keywords: Cancer; deficiency; reference value; vitamin D
Corresponding Author: Aytekin A.