Vitamin D status in adult patients with nonmelanoma skin cancer in Cape Town, South Africa: a cross-sectional study.

Background: Ultraviolet (UV) radiation is the most important environmental risk factor for the development of nonmelanoma skin cancer (NMSC). UV radiation is, however, also vital in the formation of vitamin D in humans. Strict sun protection advised to skin cancer patients may lead to vitamin D deficiency, yet vitamin D may have a protective effect against cancer formation.

Objectives: The primary aim was to determine whether patients with nonmelanoma skin cancer at our institution were vitamin D deficient.

Methods: 25-Hydroxyvitamin D (25[OH]D) levels were determined in 109 patients with a diagnosis of basal cell carcinoma (BCC) and/or squamous cell carcinoma (SCC) during the summer and winter of 2015 at the Tygerberg Academic Hospital in Cape Town, South Africa. Associations between clinical and epidemiological data and the 25(OH)D level results were investigated. Vitamin D deficiency was defined as total 25(OH)D levels <20 ng/mL (<50 nmol/L).

Results: It was found that 49.5% of NMSC patients were vitamin D deficient, and 41.3% had insufficient vitamin D levels. Females were more likely than males to be vitamin D deficient (P = 0.047). Winter was significantly associated with vitamin D deficiency, compared to summer (OR = 4.81, 95%CI = 2.09-11.09, P <0.001). Having a previous SCC appeared associated with not being vitamin D deficient (OR = 0.46, 95%CI = 0.20-1.11, P = 0.084).

Conclusions: The findings highlight the need for the development of recommendations and guidelines on sun protection in patients with NMSC, while still ensuring an adequate vitamin D status. High risk factors included winter and female gender.