143MO - Risk of lung cancer among current smokers by pack-year smoking: A cohort study with 23 years of follow-up

Background

We have recently demonstrated that current heavy smokers with >20 pack-year (PY) smoking history (median, 48.8, IQR, 31.6–57.0 PY) and non-heavy smokers (<20 PY; median, 11.4; IQR, 7.3–14.4 PY) have about 40- and 10-times higher risk of lung cancer, respectively (JAMA-Oncol. 2022; 8:1428–1437). In the current study, we examined the magnitude of the graded risk increase associated with PY of smoking among current smokers.

Methods

Of the 2505 community-dwelling older current smokers (mean age, 73 ± 5.7 years, 69% women, 17% African American) in the Cardiovascular Health Study (CHS), 1973 were never-smokers. The 532 current smokers were categorized based on PY smoking into: <20 (n = 95), 20–39 (n = 157), 40–59 (n = 181) and ≥60 (n = 94). Cause-specific HR (95% CI) for incident lung during 23 years of follow-up were estimated for the 4 groups (reference: never-smokers) based on Cox regression model, adjusting age, sex, race and competing risk of death.

Results

Incident lung cancer occurred in 0.5% of never smokers, and 5.0%, 14.6%, 17.7% and 16.0% of those with <20, 20–39, 40–59, and ≥60 PY smoking history, respectively. Compared with never smokers, cause-specific HRs (95% CIs) for incident lung cancer in the 4 groups with <20, 20–39, 40–59, and ≥60 PY smoking history were 9.73 (3.27–28.99), 30.33 (14.25–64.53), 42.97 (20.76–88.94), and 46.02 (20.08–105.48), respectively.

Conclusions

The risk of lung cancer among current smokers with <20 PY smoking for whom low-dose computed tomography screening is not recommended is high, but the risk was 3 and 4 times higher in those 20–39 and 40–59 PY, but plateaued for those with ≥60 PY. This study underscores the importance of smoking abstinence and early cessation.

Legal entity responsible for the study

The authors.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.