Meta-analysis of melanoma incidence in the United States: demographic variation and relationship with UV index and latitude

Pritchard, Charles Thomas (2014) Meta-analysis of melanoma incidence in the United States: demographic variation and relationship with UV index and latitude. Undergraduate thesis, under the direction of Carol Britson from Biology, The University of Mississippi.

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Abstract

A link between exposure to ultraviolet (UV) radiation and melanoma skin cancer formation has generally been accepted in the scientific community, but precise quantification of such a link into a predictive equation is difficult to find in scientific literature. It was the aim of this study to determine if a quantifiable relationship exists between UV exposure and melanoma rates in the United States. Prior to the initiation of this study, it was hypothesized that existing predictive equations using accumulated UV index and latitude for general skin cancer incidence (i.e., including both melanoma and non-melanoma skin cancers) in Chile would be effective in predicting melanoma incidence rates in the United States. It was also hypothesized that melanoma rates for specific locations in the United States are related to the latitudes and accumulated UV index values for those locations, respectively. After accumulated UV index values, latitudes, and melanoma incidence rates for locations across the United States were obtained, regression analyses were performed in Microsoft Excel 2010® between accumulated UV index, latitude, and melanoma incidence rates for all demographic groups combined as well as differing demographic groups. The Chilean skin cancer equations (Rivas equations) were found to have no predictive power for melanoma rates in the United States. The only demographic group which had a significant relationship with accumulated UV index and latitude was American Indian or Alaska Native. For the remaining ethnicities, the regression analyses failed to reject the null hypotheses. Due to a variety of confounding variables and the limitations of the available data, a quantifiable relationship between UV exposure and melanoma might be determined only by more complex methodology. Factors such as skin color variation within each listed ethnicity, differences in UV exposure patterns between individuals, and inconsistent reporting to cancer registries by dermatologists may preclude the formation of simple predictive equations for melanoma incidence. Future research which incorporates individuals’ behaviors (e.g., time spent in the sun) may have more success.

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