Colorectal cancer is the second leading cause of cancer death in the United States. While less common than either prostate or breast cancer, colorectal cancer shows survival rates that are substantially worse, primarily due to late stage at diagnosis. The contribution of tobacco exposures in the cause of colorectal cancer is controversial. Early studies generally reported no association, but over the last decade, evidence suggests elevated risks of colorectal cancer associated with active smoking after a very long induction period. Furthermore, evidence suggests that the effects of active smoking may differ by anatomic site (rectal vs. colon) and subsite within the colon, as well as by sex. The relationship of passive smoking exposures to colorectal cancer risk remains virtually unexplored. This study takes advantage of the enormous data resources available for the California Teachers Study cohort, for whom extensive lifetime histories of active and passive smoking exposures have been collected, to examine the risk of colorectal cancer associated with active and passive smoking exposures. These analyses will address some critical gaps in our understanding of the role of active smoking in colorectal cancer causes and will be the largest, most comprehensive analysis of passive smoking exposures and colorectal cancer to date.
Peggy Reynolds, Ph.D. (Principal Investigator), David Nelson, Ph.D.
California Tobacco Related Disease Research Program