Sun exposure has been consistently implicated in the development of non-melanoma skin cancers, but its role in melanoma etiology remains controversial, and is complicated by poorly understood genetic and behavioral factors. Melanoma incidence continues to increase (it is now the 4th most common cancer among males in California). Efforts to reduce melanoma incidence through sun exposure avoidance have had limited success, underscoring our lack of understanding of the true mechanisms of melanogenesis. Melanoma epidemiology is based on retrospective studies: recall bias probably explains associations between sunburn (almost always self-reported) and melanoma. Moreover, sun burn represents only excessive exposure to solar radiation, while sun-induced DNA damage potentially occurs across all levels of intensity: there is no accepted method for directly measuring sun exposure in epidemiological studies. In order to better understand the etiology of melanoma (particularly the role of sun exposure), valid methods of assessing both current and historical sun exposure are needed. While genetic factors probably play some role in melanogenesis, no study has yet managed to distinguish genetic from sun exposure-related risks. We will address both these issues in a case-control study of identical twins (nested in an established population-based cohort of 52,000 twins in California) assessing the role of sun exposure in melanoma etiology in the absence of genetic effects. Historical sun exposure will be assessed by combining residential history with novel fine-layer interpolated solar radiation level using GIS: we have already shown this method significantly reduces misclassification and recall bias. We will measure the actual impact of solar radiation on the skin, measuring UV- induced epidermal damage in tumor specimens noting differences in risk with varying UV intensity and wavelength. These results have the potential to improve primary prevention of melanoma and other skin cancers, and to direct the research team's future work on gene-environment interactions relevant to melanogenesis. We will measure the actual impact of solar radiation on the skin, measuring ultra-violet (UV)-induced epidermal damage in tumor specimens noting differences in risk with varying UV intensity and wavelength, and estimating the risk of melanoma with lifetime and age- specific exposures to specific wavelengths of UV. These results have the potential to improve primary prevention of melanoma and other skin cancers by indicating the appropriate means of avoiding harmful UV exposure, and to direct the research team's future work on gene-environment interactions relevant to melanogenesis.

Agency
National Institute of Health (NIH)
Institute
National Institute of Environmental Health Sciences (NIEHS)
Type
Research Project (R01)
Project #
5R01ES015552-02
Application #
7545842
Study Section
Epidemiology of Cancer Study Section (EPIC)
Program Officer
Mcallister, Kimberly A
Project Start
2008-01-01
Project End
2012-12-31
Budget Start
2009-01-01
Budget End
2009-12-31
Support Year
2
Fiscal Year
2009
Total Cost
$366,750
Indirect Cost
Name
University of Southern California
Department
Public Health & Prev Medicine
Type
Schools of Medicine
DUNS #
072933393
City
Los Angeles
State
CA
Country
United States
Zip Code
90089
Chavez-Macgregor, Mariana; Clarke, Christina A; Lichtensztajn, Daphne et al. (2013) Male breast cancer according to tumor subtype and race: a population-based study. Cancer 119:1611-7
Richards, Thomas B; Johnson, Christopher J; Tatalovich, Zaria et al. (2011) Association between cutaneous melanoma incidence rates among white US residents and county-level estimates of solar ultraviolet exposure. J Am Acad Dermatol 65:S50-7
Hausauer, Amelia K; Swetter, Susan M; Cockburn, Myles G et al. (2011) Increases in melanoma among adolescent girls and young women in California: trends by socioeconomic status and UV radiation exposure. Arch Dermatol 147:783-9
Pollitt, Ricardo A; Clarke, Christina A; Swetter, Susan M et al. (2011) The expanding melanoma burden in California hispanics: Importance of socioeconomic distribution, histologic subtype, and anatomic location. Cancer 117:152-61
Clarke, Christina A; Glaser, Sally L; Gomez, Scarlett L et al. (2011) Lymphoid malignancies in U.S. Asians: incidence rate differences by birthplace and acculturation. Cancer Epidemiol Biomarkers Prev 20:1064-77
Clarke, Christina A; Moy, Lisa M; Swetter, Susan M et al. (2010) Interaction of area-level socioeconomic status and UV radiation on melanoma occurrence in California. Cancer Epidemiol Biomarkers Prev 19:2727-33
Worswick, Scott Drayton; Cockburn, Myles; Peng, David (2008) Measurement of ultraviolet exposure in epidemiological studies of skin and skin cancers. Photochem Photobiol 84:1462-72
Hamidi, Reyhaneh; Cockburn, Myles G; Peng, David H (2008) Prevalence and predictors of skin self-examination: prospects for melanoma prevention and early detection. Int J Dermatol 47:993-1003