Lung Cancer Risk and Demographic Characteristics of Current 20-29 Pack-year Smokers: Implications for Screening.

BACKGROUND Based on current recommendations, 30+ pack-years of smoking are required for eligibility for low-dose CT (LDCT) lung cancer screening; former smokers must have quit within 15 years. We investigated whether current smokers with 20 to 29 pack-years have similar lung cancer risks as eligible former smokers and also whether they have a different demographic profile. METHODS The Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) was a randomly assigned screening trial of subjects age 55 to 74 years with chest radiographs (CXR) used for lung cancer. Subjects completed a baseline questionnaire containing smoking history questions. Cox proportional hazards models, adjusted for age and sex, were utilized to estimate hazard ratios (HRs) for various smoking history groups. Next, we utilized the National Health Interview Survey (NHIS), which inquired about smoking history and race/ethnicity, to analyze the demographic profiles of various high-risk smoking history categories. All statistical tests were two-sided. RESULTS The PLCO cohort included 18 114 former and 12 243 current LDCT-eligible smokers, plus 2283 20- to 29-pack-year current smokers. The hazard ratio for 20- to 29-pack-year current smokers compared with eligible (30+ pack-year) former smokers was 1.07 (95% confidence interval [CI] = 0.75 to 1.5). Based on the NHIS, 10 million persons in the United States are currently LDCT eligible; an additional 1.6 million (16%, 95% CI = 13.6% to 19.0%) are 20- to 29-pack-year current smokers. The percentage increase in eligibles if 20- to 29-pack-year current smokers were included was substantially greater for women than men (22.2%, 95% CI = 17.9% to 26.7%; vs 12.2%, 95% CI = 9.3% to 15.3%, P < .001) and for minorities than non-Hispanic whites (30.0%, 95% CI = 24.2% to 36.0%; vs 14.1%, 95% CI = 11.1% to 17.0%, P < .001). CONCLUSION The potential benefits and harms of recommending LDCT screening for 20 to 29-pack-year current smokers should be assessed.

[1]  D. Wood,et al.  National Comprehensive Cancer Network (NCCN) Clinical Practice Guidelines for Lung Cancer Screening. , 2015, Thoracic surgery clinics.

[2]  B. Kramer,et al.  Lung cancer risk by years since quitting in 30+ pack year smokers , 2015, Journal of medical screening.

[3]  V. Moyer.  Screening for Lung Cancer: U.S. Preventive Services Task Force Recommendation Statement , 2014, Annals of Internal Medicine.

[4]  P. Lee,et al.  How rapidly does the excess risk of lung cancer decline following quitting smoking? A quantitative review using the negative exponential model. , 2013, Regulatory toxicology and pharmacology : RTP.

[5]  Michael J Thun,et al.  50-year trends in smoking-related mortality in the United States. , 2013, The New England journal of medicine.

[6]  J. Gohagan,et al.  Screening by chest radiograph and lung cancer mortality: the Prostate, Lung, Colorectal, and Ovarian (PLCO) randomized trial. , 2011, JAMA.

[7]  H. D. de Koning,et al.  NELSON lung cancer screening study , 2011, Cancer imaging : the official publication of the International Cancer Imaging Society.

[8]  C. Gatsonis,et al.  Reduced Lung-Cancer Mortality with Low-Dose Computed Tomographic Screening , 2012 .

[9]  M. Thun,et al.  The change in excess risk of lung cancer attributable to smoking following smoking cessation: an examination of different analytic approaches using CPS-I data , 2008, Cancer Causes & Control.

[10]  P. Pinsky.  Racial and ethnic differences in lung cancer incidence: how much is explained by differences in smoking patterns? (United States) , 2006, Cancer Causes & Control.

[11]  Richard Doll,et al.  Smoking, smoking cessation, and lung cancer in the UK since 1950: combination of national statistics with two case-control studies , 2000, BMJ : British Medical Journal.

[12]  N H Ng'andu,et al.  An empirical comparison of statistical tests for assessing the proportional hazards assumption of Cox's model. , 1997, Statistics in medicine.

[13]  B. Gillespie,et al.  Patterns of absolute risk of lung cancer mortality in former smokers. , 1993, Journal of the National Cancer Institute.

[14]  Bernard Maitre,et al.  Screening by Chest Radiograph and Lung Cancer Mortality : The Prostate , Lung , Colorectal , and Ovarian ( PLCO ) Randomized Trial , 2022 .