Vitamin D serum levels and non-melanoma skin cancer risk

[Translated article] Vitamin D and Skin Cancer: A Controversial Society. Literature Update and Review

Vitamin D (VD) deficiency has been associated with various tumors. However, the association between VD and skin cancer is controversial. Although in non-melanoma skin cancer, adequate or even high levels of VD can be associated with a higher risk of developing tumors, this could be biased by the direct association between sun exposure and VD levels. Regarding melanoma, results are contradictory. Most studies analyzed state that higher levels of VD could reduce the risk of melanoma, be associated with melanomas with better prognosis and with an enhanced antitumor response, and also with fewer adverse events associated with melanoma immunotherapy. However, prospective studies of adequate methodological quality are still needed to assess the association between VD levels and its supplementation and development/prognosis in skin cancer.

Vitamin D and Skin Cancer: A Controversial Society. Literature Update and Review

Vitamin D (VD) deficiency has been associated with various tumors. However, the association between VD and skin cancer is controversial. Although in non-melanoma skin cancer, adequate or even high levels of VD can be associated with a higher risk of developing tumors, this could be biased by the direct association between sun exposure and VD levels. Regarding melanoma, results are contradictory. Most studies analyzed state that higher levels of VD could reduce the risk of melanoma, be associated with melanomas with better prognosis and with an enhanced antitumor response, and also with fewer adverse events associated with melanoma immunotherapy. However, prospective studies of adequate methodological quality are still needed to assess the association between VD levels and its supplementation and development/prognosis in skin cancer.

Non-Melanoma Skin Cancer and Vitamin D: The "Lost Sunlight" Paradox and the Oxidative Stress Explanation

UV radiation (UVR) is responsible for inducing both harmful and beneficial effects on skin health. Specifically, it has been reported to disrupt oxidant and antioxidant levels, leading to oxidative stress conditions in skin tissue. This phenomenon might trigger photo-carcinogenesis, resulting in melanoma, NMSC (non-melanoma skin cancer), such as BCC (basal cell carcinoma) and SCC (squamous cell carcinoma), and actinic keratosis. On the other hand, UVR is essential for the production of adequate vitamin D levels, a hormone with important antioxidant, anticancer and immunomodulatory properties. The exact mechanisms implicated in this two-fold action are not well understood, as there still no clear relation established between skin cancer and vitamin D status. Oxidative stress seems to be a neglected aspect of this complex relation, despite its role in both skin cancer development and vitamin D deficiency. Therefore, the aim of the present study is to examine the correlation between vitamin D and oxidative stress in skin cancer patients. A total of 100 subjects (25 with SCC, 26 with BCC, 23 with actinic keratosis, and 27 controls) were assessed in terms of 25-hydroxyvitamin D (25(OH) D) and redox markers such as thiobarbituric acid reactive substances (TBARS), protein carbonyls, total antioxidant capacity (TAC) in plasma, glutathione (GSH) levels and catalase activity in erythrocytes. The majority of our patients revealed low vitamin D levels; 37% of the subjects showed deficiency (<20 ng/mL) and 35% insufficiency (21-29 ng/mL). The mean 25(OH) D level of the NMSC patients (20.87 ng/mL) was also found to be significantly lower (p = 0.004) than that of the non-cancer patients (28.14 ng/mL). Furthermore, higher vitamin D levels were also correlated with lower oxidative stress (positive correlation with GSH, catalase activity TAC index and negative correlation with TBARS and CARBS indices). NMSC patients diagnosed with SCC showed lower catalase activity values compared to non-cancer patients (p < 0.001), with the lowest values occurring in patients with a chronic cancer diagnosis (p < 0.001) and vitamin D deficiency (p < 0.001). Higher GSH levels (p = 0.001) and lower TBARS levels (p = 0.016) were found in the control group compared to the NMSC group, and to patients with actinic keratosis. Higher levels of CARBS were observed in patients with SCC (p < 0.001). Non-cancer patients with vitamin D sufficiency showed higher TAC values compared to non-cancer patients with vitamin D deficiency (p = 0.023) and to NMSC patients (p = 0.036). The above-mentioned results indicate that NMSC patients reveal increased levels of oxidative damage markers compared to control levels, while vitamin D status plays a critical role in the determination of individuals' oxidative status.

Benefits and Risks of Sun Exposure to Maintain Adequate Vitamin D Levels

Vitamin D is a hormone that can be generated in the skin upon ultraviolet light exposure or ingested through supplementation. Vitamin D deficiency may have numerous deleterious effects on health. Sun avoidance strategies should be avoided due to the unwanted health risks associated with hypovitaminosis D. We present an objective investigation of the benefits and risks of using sun exposure to increase vitamin D levels and how it impacts human health. A review of the literature was conducted using Embase and PubMed to examine the relationship between UV exposure, vitamin D levels, health benefits, and risks. UV exposure is the primary method of boosting serum vitamin D levels, which accounts for numerous health benefits. Higher levels of vitamin D are associated with protection against cancer development, including melanoma. Latitude, season, skin color, and sun protection determine UV absorption and vitamin D production. Public health sun protection guidelines decrease the incidence of skin cancer, but sun avoidance can cause hypovitaminosis D. Serum vitamin D levels less than 16 nmol/L increase morbidity through increased non-cutaneous disease. Sun protection strategies should still be implemented to reduce skin cancer, and sunscreen only minimally lowers vitamin D production. Vitamin D deficiency can increase chronic diseases and cancer, while adequate vitamin D levels can help prevent them. UV exposure and vitamin D production are dependent on many factors. Increasing UV exposure without causing sunburn maximizes vitamin D production.

Serum Vitamin D Levels Explored in the Latvian Cohort of Patients with Basal Cell Carcinoma Linked to the Sonic Hedgehog and Vitamin D Binding Protein Cutaneous Tissue Indices

Ultraviolet radiation is known as one of the major contributors to skin malignancies, including basal cell carcinoma (BCC), which is the most common type of skin cancer. It is a heterogeneous tumor, which presents with various types that are stratified into low- and high-risk tumors. Sunlight is important for overall health and vitamin D synthesis in the skin, whereas deviations from the optimal level of vitamin D are shown to be associated with the risk of the development of BCC. The accumulating evidence suggests the ability of vitamin D to antagonize the Sonic Hedgehog (SHH) signaling, the key tumor pathway, and play a protective role in the development of BCC. Additionally, a vitamin D binding protein (DBP) is shown to be implicated in the complex regulation of vitamin D. Here, we aimed to explore serum vitamin D in patients with different primary and recurrent BCC of the head and neck and investigate cutaneous DBP and SHH indices, confirmed immunohistochemically in these subjects. According to the results, 94.9% of the Latvian cohort of BCC patients were found to be deficient in vitamin D. No significant differences in serum vitamin D levels were found between genders, primary and recurrent tumors, and different types of BCC. Serum vitamin D was inversely associated with tumor size. Susceptible male individuals with low blood vitamin D levels were recognized at risk of developing aggressive and recurrent BCC confirmed by the use of hierarchical clustering analysis. In smaller tumors with a favorable course, such as superficial and nodular BCC, the association between high DBP and low SHH tissue expression was found, providing supportive evidence of the existence of a link between vitamin D, proteins involved in its metabolism, as exemplified by the DBP and SHH signaling pathway. The assumption of a deficiency in the protective effect of vitamin D in patients with high-risk BCCs was proposed in low DBP and high SHH tissue indices. New extensions to existing knowledge and characterization of the BCC signaling pathways and their cross-talk with vitamin D are warranted when searching for a preferential effect of vitamin D on skin cancer.