We propose to prospectively assess risk factors and early detection markers for GDC by conducting the Chile Biliary Longitudinal Study (BiLS), a cohort study of 6250 individuals with gallstones from the high-risk southern-central region of Chile. Because women are twice as likely to have gallstones and twice as likely to have gallbladder cancer as men, we plan to maximize our screening efficiency and number of outcomes by screening and enrolling women for the gallstone cohort. This approach is reasonable given that the female gender bias for gallbladder cancer is largely thought to be due to the gender bias for gallstones, suggesting that in the presence of gallstones, the risk of gallbladder cancer is the same for men and women. In addition, Chile is conducting a general population cohort in a small town in the high-risk area, and we can use the men with gallstones enrolled by the Chilean study to compare to the women in our study. The cohort will be complemented by an incident case-control study of 300 gallbladder cancer cases and 450-500 controls with and without gallstones obtained, and we will include men in this arm of the study, which will facilitate exploratory sex-stratified analyses. We plan to enroll women with gallstones over 2 years and follow them for 6 years, conducting visits every other year to collect data on the primary exposures of interest, inflammatory markers and ultrasound characteristics, as well as additional exposures of interest, such as infections, genetics, and environmental exposures (e.g., aflatoxin, pesticides).