CARET: THE SEATTLE STUDY CENTER

CARET is an ongoing double-blind lung cancer chemoprevention trial of the efficacy and safety of tide combination of 30 mg beta-carotene and 25,000 IU retinyl palmitate daily in two high-risk populations: (a) male and female current and former smokers recruited primarily from insurance-based sources, and (b)males with extensive occupational asbestos exposure recruited primarily from employment-based sources. We have documented successful recruitment, excellent adherence, and minimal side effects in over 15,000 participants randomized thus fur at six study centers. Through 30 April, 1993, CARET has randomized 4,000 asbestos-exposed workers, exceeding accrual goals at all five CARET asbestos centers, and 11,105 heavy smokers. Seattle and Portland have exceeded their heavy smoker goals, and Irvine is on track to achieve its goal in July 1994. During the final five-year period, CARET will focus on retention, adherence to protocol, ascertainment of endpoints, monitoring of key design parameters, closeout of the trial, and analysis and publication. Projections indicate that with 14,240 smokers and 4,010 asbestos-exposed participants and 114,100 person-years of follow-up through February 1998, CARET will be capable of detecting a. 23% reduction in lung cancer incidence in the two high-risk populations combined, and 27%, 49%, 32%, and 35% reductions in the smokers, female smokers, male smokers, and asbestos-exposed subgroups, respectively. The Seattle Study Center has a unique responsibility for following the participants in the original smoker and asbestos-exposed worker pilot studies, as well as Seattle's share of the CARET Efficacy cohort. Of the 1,845 Pilot participants recruited during 1985-1988, 1,524 (the Vanguard cohort) continued active participation. These Vanguard participants are monitored closely to evaluate toxicity potentially related to the cumulative dose of the study vitamins. The Seattle' Study Center has surpassed its CARET Efficacy recruitment goals of smokers and asbestos- exposed workers, in part due to our recently approved access to recruit members of the American Association of Retired Persons. The Study Center will continue to emphasize the retention of participants and adherence to the CARET protocol. The collection of endpoints, which will be increasing during the final four years, has also become more prominent as recruitment activities cease. Our data and processing unit will focus on timely submission and reconciliation of data with the Coordinating Center. As the largest study center of CARET, we will play a prominent role in analysis and publication of CARET results.