The main analyses included 635.031 men and women drawn from Cancer Prevention Study II. an ongoing prospective mortality study of 1.185,124 persons enrolled by 77.000 volunteers of the American Cancer Society in the
full of 1982 . Participants in the study were usually friends, neighbors, or acquaintances of the volunteers. Enrollment took place in all 50 slates, the District of Columbia, and Puerto Rico. Families were enrolled if at least one household member was 45 years old or older and all enrolled members were 30 years old or older. The average age of the participants at enrollment was 57 years