Fundamental questions to sun protection: A continuous education symposium on vitamin D, immune system and sun protection at the University of Zürich

Since exposure to sunlight is a main factor in the development of non-melanoma skin cancer and there are associations between malignant melanoma and short-term intense ultraviolet (UV) exposure, particularly burning in childhood, strict protection from UV-radiation is recommended. However, up to 90% of all requisite vitamin D has to be formed within the skin through the action of the sun—a serious problem, for a connection between vitamin D deficiency, demonstrated in epidemiological studies, and various types of cancer and other diseases has been confirmed. A UVB-triggered skin autonomous vitamin D3 synthesis pathway has recently been described, producing the active Vitamin D metabolite calcitriol. This cutaneous vitamin D3 pathway is unique. Keratinocytes and dendritic cells can convert vitamin D to calcitriol. Cutaneous T cells activated in the presence of calcitriol express the chemokine receptor CCR10 attracting them to the chemokine CCL27 that keratinocytes express selectively in the epidermis, and migrate from dermal layers of the skin to the epidermis under UV radiation. Thus, calcitriol has endocrine roles beyond its calciotropic action, including cell growth and cancer prevention. Therefore, strict sun protection procedures to prevent skin cancer may induce the risk of vitamin D deficiency. As there is evidence that the protective effect of less intense solar radiation can outweigh its mutagenic effect, better balanced approaches to sun protection should be sought

Time trends and latitude dependence of uveal and cutaneous malignant melanoma induced by solar radiation

In order to evaluate the role of solar radiation in uveal melanoma etiology, the time and latitude dependency of the incidence rates of this melanoma type were studied in comparison with those of cutaneous malignant melanoma (CMM). Norway and several other countries with Caucasian populations were included. there is a marked north-south gradient of the incidence rates of CMM in Norway, with three times higher rates in the south than in the north. No such gradient is found for uveal melanoma. Similar findings have been published for CMM in other Caucasian populations, with the exception of Europe as a whole. In most populations the ratios of uveal melanoma incidence rates to those of CMM tend to decrease with increasing CMM rates. This is also true for Europe, in spite of the fact that in this region there is an inverse latitude gradient of CMM, with higher rates in the north than in the south

Phototherapy with UVB narrowband, UVA/UVBnb, and UVA1 differentially impacts serum 25-hydroxyvitamin-D3

BACKGROUND: Ultraviolet (UV) B radiation increases serum 25-hydroxyvitamin-D3 [25(OH)D], but the influence of UVA1 and UVA/narrowband UVB (UVBnb) phototherapy on serum vitamin D is unknown. OBJECTIVE: We sought to investigate the influence of UVBnb, UVA1, and UVA/UVBnb phototherapy on serum levels of 25(OH)D and related parameters in patients with an inflammatory skin condition. METHODS: 25(OH)D, as well as calcium, parathormone, phosphate, and albumin were measured before therapy, 2 weeks after start, and after completion of the phototherapy. Diagnoses were divided in 4 groups: atopic dermatitis, psoriasis, morphea, and others. RESULTS: We surveyed 116 dermatologic patients undergoing phototherapy with UVA1 (n = 38), UVA/UVBnb (n = 30), or UVBnb (n = 48) 2 to 3 times a week for 53 to 90 days. UVBnb phototherapy increased serum 25(OH)D from 22.1 to 39.5 ng/mL after the therapy (P < .001). The lower the baseline 25(OH)D level was, the steeper the increase in 25(OH)D was upon application of UVBnb phototherapy. UVA/UVBnb therapy also increased serum 25(OH)D, from 23.9 to 50.3 ng/mL (P = .003). Conversely, in the UVA1 therapy group, 25(OH)D serum levels decreased significantly from 21.9 to 19.0 ng/mL (P < .001). LIMITATIONS: The study design was open trial without randomization. An influence of a precise skin disease cannot be excluded because of the heterogeneous diagnoses. Bias may have arisen from patient preference for treatment at our center, referral, unrecognized differences in underlying skin disease, and other factors. CONCLUSION: Phototherapy with UVBnb and UVA/UVBnb increased 25(OH)D serum level significantly. UVA1 therapy alone induced a reduction in serum 25(OH)D concentrations