The Relationship Between Vitamin D Deficiency and Laryngeal Cancer in Iran: A Case-control Study in Mashhad

Background: Despite the high prevalence of head and neck cancers in Iran, no studies have been conducted to investigate the relationship between vitamin D levels and these cancers. Many Iranians suffer from vitamin D deficiency, which underscores the importance of conducting these studies in Iran. Objectives: This study aims at investigating the relationship between vitamin D levels and laryngeal cancer. Methods: This 1: 1 matched case-control study included 216 patients in Mashhad, Iran, who had not consumed vitamin D supplements for 3-months before study onset. Participants were grouped in 2 categories; the case group, which consisted of patients with laryngeal cancer whose squamous cell carcinoma was confirmed pathologically for the first time (new cases), and the control group, which consisted of individuals who did not have any cancer at the time of the study, confirmed by indirect laryngoscopy, and were identical to the patient group in terms of other risk factors for laryngeal cancer (smoking and alcohol abuse). First, the relevant checklist (including age, occupation, consumption of tobacco, alcohol use, etc., history of contact with mustard gas, wood, stone, metal, and cement industry, as well as history of reflux in the individual and cancer in relatives) was completed for all case and control group members. After taking blood samples, they were evaluated for serum levels of vitamin D3. Data were analyzed using chi-square, Mann-Whitney U or independent sample t-tests. Logistic regression was also used to determine the relation between vitamin D level and laryngeal cancer. Results: Mean age, sex and risk factors of laryngeal cancer were not significantly different between the two groups. Vitamin D level was significantly lower in patients with laryngeal cancer compared to control group (16.02 ± 3.62 ng/mL vs 25.19 ± 3.40 (P < 0.001)). Logistic regression analysis showed that vitamin D level is independently related to laryngeal cancer and has a protective effect on this neoplasm (OR = 0.54, 95%CI: 0.46 - 0.63, P < 0.001). Conclusions: A lower vitamin D level may be related to laryngeal cancer. However, the role of vitamin D deficiency as a risk factor for head and neck cancers and whether the treatment of this condition could prevent the incidence of such cancers is a matter of future investigations.