The American Cancer Society first began conducting long-term prospective studies in the 1950s. The participants provide initial lifestyle, medical, or behavioral information, and then are followed over time to assess their health outcomes to determine how those outcomes are related to the previously collected data. Previous long-term Society studies have played a major role in cancer prevention, including demonstrating the link between cigarette smoking and lung cancer, the impact of being overweight or obese on risk of cancer occurrence and death, and much more.​