Sun exposure before and after a diagnosis of cutaneous malignant melanoma: estimated by developments in serum vitamin D, skin pigmentation and interviews.

Abstract

Previous studies on ultraviolet radiation (UVR) exposure before and after a diagnosis of cutaneous malignant melanoma (CMM) have been based primarily on questionnaires. Objective measures are needed. To assess changes in UVR exposure in patients with CMM using objective surrogate parameters in a descriptive study. Ten patients recently diagnosed with CMM during the 5 months (autumn and winter) preceding study start in February 2009; 21 patients diagnosed from 12 months to 6 years before study start; and 15 controls, who matched the recently diagnosed patients on age, sex, residential area, constitutive skin type and occupation completed the investigations. UVR exposure before and after diagnosis of CMM was assessed using measures of serum 25-hydro vitamin D [25(OH)D], skin pigmentation and by interviews. Winter 25(OH)D was used as a surrogate parameter of UVR exposure the previous summer - the summer before CMM diagnosis in recently diagnosed patients. Winter 25(OH)D was significantly higher among recently diagnosed patients compared with controls (P = 0·02, R² = 0·60) and patients diagnosed up to 6 years earlier (P = 0·01). The increase in 25(OH)D during the summer after diagnosis was significantly lower for recently diagnosed patients than for controls (P = 0·005, R² = 0·51) and patients diagnosed up to 6 years earlier (P = 0·008). No difference was found in summer 25(OH)D between the groups. Our findings suggest that patients with CMM had a higher UVR exposure the summer before diagnosis than did controls and patients diagnosed up to 6 years earlier, and that after diagnosis UVR exposure fell to the level of controls in patients with CMM.