PS 1-36 SMOKING HISTORY AND ELIGIBILITY FOR LUNG CANCER SCREENING: HOW CLOSE IS CLOSE ENOUGH?

Sunday, October 23, 2016
Bayshore Ballroom ABC, Lobby Level (Westin Bayshore Vancouver)
Poster Board # PS 1-36

Robert J. Volk, Tito R. Mendoza and Therese B. Bevers, MD, The University of Texas MD Anderson Cancer Center, Houston, TX
Purpose: We examined the reliability of smokers’ self-reported tobacco use, specifically the 30 pack-year smoking history criterion, and its impact on eligibility for lung cancer screening. 

Methods: Smokers ages 55 to 77 years were recruited through a tobacco treatment program, a lung cancer screening program, and local advertisements. Subjects were asked to report on their tobacco use histories at a baseline assessment and again one month later. Subjects responded to the following questions: Have you smoked at least 100 cigarettes in your entire lifetime? Do you currently smoke? How many years have/did you smoke? On average, how many cigarettes do/did you smoke per day? Eligible subjects had to have smoked at least 100 cigarettes in their lifetime. Subjects who were current nonsmokers were asked how many years ago they had quit. Reliability of reported pack-year smoking history was estimated using the intraclass correlation coefficient (ICC) and confidence limits were calculated for various pack-year smoking history estimates.

Results: The mean age of the 102 subjects was 63.6 years, with roughly 10% over 70 years. At the baseline assessment, 62 (60.8%) of subjects reported a pack-year smoking history of 30 or greater, and at the 1-month follow-up 64 (62.7%) subjects reported at least a 30 pack-year smoking history (Kappa = .83, P<.001). The reliability of self-reported smoking history was high (ICCs greater than .90). About 8% of smokers were eligible at one time period but not the other. Confidence limits were wide; for example, for a 25 pack-year smoking history the upper 68% and 95% confidence limits exceed the 30 pack-year threshold.

Conclusions: Recommendations about lung cancer screening endorse a 30 pack-year smoking history threshold in the determination of eligibility for screening with low-dose CT. When concerns about the imprecision of self-reported smoking history are coupled with other considerations, a lower pack-year history threshold for lung cancer screening eligibility may be justified. Clinicians should carefully assess patients’ smoking history, and be cautious when recommending screening for patients with a pack-year smoking history under 30 because the net benefits of screening may be less than for heavier smokers.