The genetics of sleep behavior and the association with breast cancer risk and aggressiveness
Vaughn, Caila B.
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Because breast cancer is such a common cancer and affects a substantial proportion of women, it is important to thoroughly understand the factors that may increase a woman’s risk. Night shift work is one factor that has been shown to increase risk of breast cancer. Because a relationship has been demonstrated between night shift work and increased risk, it has been hypothesized that this results from getting less sleep, which has been documented among shift workers. However findings regarding the relationship between sleep duration and breast cancer risk are not consistent. Few studies have examined measures of sleep other than duration with breast cancer risk. And though there is a genetic component to sleep behavior, few studies have conducted genome-wide association studies of sleep-associated phenotypes. Furthermore, though sleep-associated genes have been implicated in cancer risk overall because, in part, of their effect on cell cycle regulation, few studies have examined sleep-related candidate-genes and breast cancer risk in a large population of women. Therefore, we performed studies to analyze three related questions. In the first study, conducted in the Western New York Exposures and Breast Cancer (WEB) study, we analyzed the association of sleep disturbance with breast cancer aggressiveness and survival (both overall mortality and breast cancer mortality). The second study utilized a genome-wide association approach to identify SNPs associated with sleep-related phenotypes in three independent subsamples from the Women’s Health Initiative (WHI). The final study was a candidate-gene study to determine if variants in circadian rhythm genes are associated with breast cancer risk in European American and African American women in WHI, and if those hypothesized associations are mediated or modified by sleep behavior.