Abstract
BACKGROUND: Self-reported smoking may not fully capture individualized risk of smoking-related cancer. Circulating proteins may reflect biological consequences of smoking. Thus, we developed a score from smoking-related proteins and evaluated its association with smoking-related cancer. METHODS: This prospective cohort study included 10,563 participants aged 47-70 years in the Atherosclerosis Risk in Communities study. Plasma proteins were measured by SomaScan. The score was constructed from proteins associated with current smoking, packyears, and/or recent quitting identified by linear regression and elastic net regression. Cox regression was used to estimate adjusted hazard ratios (aHR) and 95% confidence intervals (CI). We confirmed the association in a case-cohort study in the European Prospective Investigation into Cancer and Nutrition (EPIC). RESULTS: aHRs comparing score quartiles Q4 to Q1 for total incidence and mortality of 13 smoking-related cancers were 3.89 (95% CI 3.06-4.96) and 5.73 (95% CI 4.08-8.06) before, and 2.28 (95% CI 1.65-3.15) and 2.07 (95% CI 1.74-4.10) after adjusting for self-reported smoking. aHRs for lung cancer were 12.1 (95% CI 7.11-20.6) and 14.2 (95% CI 7.58-26.8) before, 3.04 (95% CI 1.59-5.81) and 4.12 (95% CI 1.99-8.53) after adjusting. In EPIC, aHRs for lung cancer were 9.47 (95% CI 6.82-13.15) before and 2.23 (95% CI 1.48-3.35) after adjusting. CONCLUSION: The smoking-related protein score provided relative risk information for smoking-associated cancers beyond self-reported smoking, which was confirmed in an independent cohort. Such a score may be considered for use in risk stratification for prevention and cancer screening in settings in which detailed smoking history cannot be obtained.