Decline of DNA damage and other biomarkers in peripheral blood following smoking cessation

Serial samples from 40 heavy smokers ( > or = pack/day for > or = 1 year) enrolled in a smoking cessation program were assayed for cotinine, polycyclic aromatic hydrocarbon (PAH)-DNA, 4-aminobiphenyl-hemoglobin (4-ABP-Hb) adducts, and glycophorin A (GPA) mutations. Blood samples were taken while subjects were smoking, and 10 weeks and 8 and 14 months after quitting. Cotinine was used to assess compliance with the cessation protocol. A significant reduction in mean PAH-DNA and 4-ABP-Hb adducts was observed after cessation in all persons who were cotinine-verified quitters ( < or = 25 ng/ml) for > or = 8 months (P < 0.05). Neither the GPA N/phi nor the GPA N/N mutation Vf was significantly reduced after smoking cessation, but results are limited by the small number (n = 18) of heterozygous individuals studied. The substantial reduction (50-75%) in PAH-DNA and 4-ABP-Hb adduct levels after quitting indicates these carcinogen adducts are reflective of smoking. Passive exposure to smoke at home was significantly associated with PAH-DNA adducts in active smokers and in ex-smokers 10 weeks after quitting (P < 0.01). The estimated half-life of the PAH-DNA adducts in leukocytes is 9-13 weeks by inspection of the mean biomarker levels from baseline and 10 weeks sample and 23 (95% confidence interval, 10-36 weeks) using a linear regression model that adjusted for background.