Vitamin D deficiency in cancer patients and predictors for screening (D-ONC study)

Vitamin D is a prohormone that is vital for calcium/phosphate balance, bone structure, and physiological functioning. Vitamin D deficiency (VDD) is an important clinical problem worldwide. However, there are no standardized protocols for screening of patients with a diagnosis of cancer. The purpose of this study is to define the prevalence of VDD in cancer patients and establish the predictors of VDD to address a specific group of patient for screening.

The study was designed as a retrospective case-control study. The patients cared in the outpatient clinic between December 2016 and May 2018 with a diagnosis of cancer were evaluated. The clinical properties and the 25(OH) D levels were evaluated. Logistic regression was used to compute odds ratios (ORs) and 95% confidence intervals (CIs) for the association between VDD and clinical parameters.

In 2 cancer centers, 706 patients with a diagnosis of cancer were evaluated. Median 25(OH) D level was 12.2 ng/mL (2.1-96.4). VDD was present in 509 (72.0%) of patients. The multivariate analysis of factors associated with VDD showed that female gender (OR: 1.5 [95% CI: 1.05-2.4], P = 0.026), low sun light exposure (OR: 1.4 [95% CI: 1.009-2.1], P = 0.045), being under palliative (OR: 1.5, [95% CI: 1.008-2.4] P = 0.04) or adjuvant setting (OR: 2.6 [95% CI: 1.3-5.1], P = 0.006), and history of gastrointestinal surgery (OR: 1.8, [95% CI: 1.03-3.2] P = 0.03) were associated with VDD. The female patients with headscarf had lower 25(OH) D levels than without group (10.5 ng/mL vs 23.4 ng/mL, P < 0.001) and they had more VDD (77.2% vs 29.4%, P < 0.001).

Our study concluded that prevalence of VDD is high in cancer patients and female gender, low sun light exposure, being under palliative or adjuvant setting, and history of gastrointestinal surgery are associated with VDD. These parameters should be used for selecting patients for screening.