Incidence of cutaneous malignant melanoma in Iranian provinces and American states matched on ultraviolet radiation exposure: an ecologic study.
Environ Pollut. 2018 Mar;234:699-706
Authors: Moslehi R, Zeinomar N, Boscoe FP
OBJECTIVES: Ultraviolet radiation (UVR), with UVB and UVA as the relevant components, is a risk factor for melanoma. Complete ascertainment and registration of melanoma in Iran was conducted in five provinces (Ardabil, Golestan, Mazandaran, Gilan and Kerman) during 1996-2000. The aim of our study was to compare population-based incidence data from these provinces with rates in the United States (US) while standardizing ambient UVR.
METHODS: Population-based rates representing all incident cases of melanoma (1996-2000) across the five Iranian provinces were compared to rates of melanoma among white non-Hispanics in the US. Overall age-standardized rates (ASR) for Iran and the US (per 100,000 person-years adjusted to 2000 world population) and standardized rate ratios (SRR) were calculated. We measured erythemally-weighted average solar UVR exposures (with contributions from both UVB and UVA range) of the five Iranian provinces using data from NASA's Total Ozone Mapping Spectrometer and selected five US states (Kentucky, Utah, Texas, Oklahoma, and Hawaii) with matching UVR exposure to each province. Incidence rates of melanoma during 1996-2000 in each Iranian province were compared to rates among white non-Hispanics in its UVR-matched US state.
RESULTS: The overall male and female ASRs of melanoma were 0.60 (95%CI: 0.56-0.64) and 0.46 (95%CI: 0.42-0.49), respectively, for Iran and 22.78 (95%CI: 22.42-23.14) and 16.61 (95%CI: 16.30-16.92) for the US. SRRs of melanoma comparing US to Iran were 37.97 (95%CI: 35.78-40.29) for males and 36.11 (95%CI: 33.69-38.70) for females, indicating significantly higher incidence in the US. ASRs and age-specific rates of melanoma for both genders were significantly lower in each Iranian province compared to its UVR-matched US state.
CONCLUSION: The markedly lower incidence rates of melanoma in Iranian provinces with similar UVR exposures to US states underscore the need for additional comparative studies to decipher the influence of other extrinsic and intrinsic factors on the risk of this malignancy.
PMID: 29241156 [PubMed - indexed for MEDLINE]
The effect of interaction of heat and UVB on human keratinocyte: Novel insights on UVB-induced carcinogenesis of the skin.
J Dermatol Sci. 2017 Nov;88(2):207-215
Authors: Lan CE, Wang YT, Lu CY, Fang AH, Wu CS
BACKGROUND: Skin cancer is an important environmentally-related health issue. Although sun exposure is closely associated with increasing environmental heat, the effects of environmental heat on the skin, especially in the context of photocarcinogenesis, has not been carefully examined.
OBJECTIVES: This study aimed to explore the effects and interactions of UVB radiation and environmental heat on photocarcinogenesis of the skin using cell and animal models.
METHODS: Cultured keratinocytes and hairless mice were exposed to different treatment conditions including UVB radiation and environmental heat. The effects of treatment on keratinocyte and mice skin were evaluated at indicated time points.
RESULTS: UVB induced DNA damage was significantly lower in keratinocytes that were pretreated in an environment with slightly elevated temperature followed by UVB treatment (Heat-UVB) as compared to UVB and UVB radiation followed by exposure to equivalent increase in environmental heat (UVB-Heat) groups. Similar phenomenon was observed in terms of keratinocyte viability. In the animal model, it was found that Heat-UVB treated mice showed delayed and reduced tumor formation as compared to the UVB and UVB-Heat treated groups. Quantum simulation analyses demonstrated that the energy required for CPD formation at environment with higher temperature required considerable higher energy as compared to CPD formation at lower temperature.
CONCLUSION: Taken together, our results demonstrated that with equivalent UVB exposure, higher temperature environment may protect cells against subsequent UVB-induced DNA damages.
PMID: 28687416 [PubMed - indexed for MEDLINE]