No effect of meat, meat cooking preferences, meat mutagens or heme iron on lung cancer risk in the prostate, lung, colorectal and ovarian cancer screening trial

Recent epidemiological studies have suggested that red and processed meat may increase the risk of lung cancer. Possible underlying mechanisms include mutagens produced during high-temperature cooking or preservation, or formed endogenously from heme iron in meat. We used data from 99,579 participants of both screened and nonscreened arms of the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, aged 55-74 years, to investigate whether meat type, cooking method, doneness level, intake of specific meat mutagens 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 2-amino-3,4,8- trimethylimidazo[4,5-f]quinoxaline] (DiMeIQx), 2-amino-1-methyl-6- phenylimidazo[4,5-b]pyridine (PhIP) and benzo(a)pyrene (B(a)P)] and heme iron are associated with lung cancer. Participants' diet was assessed prospectively using a 124-item food frequency questionnaire and an additional meat-cooking module. Dietary data were used in conjunction with a database to estimate intake of MeIQx, DiMeIQx, PhIP, B(a)P and heme iron. After up to 8 years of follow-up, 782 incident lung cancer cases were ascertained. Lung cancer risk was not associated with the consumption of either red (men: HR_{Q 5 vs. Q1} = 1.11, 95% CI = 0.79-1.56, P_trend = 0.42; women: HR_{Q5 vs. Q1} = 1.30, 95% CI = 0.87-1.95, P_trend = 0.65) or processed meat (men: HR_{Q 5 vs. Q1} = 1.12, 95% CI = 0.83-1.53, P_trend = 0.22; women: HR_{Q5 vs. Q1} = 0.98, 95% CI = 0.68-1.41, P_trend = 0.32) in multivariable models. High-temperature cooking methods, level of meat doneness, meat mutagens and heme iron had no effect on lung cancer risk. In this population, we found no association between meat type, cooking method, doneness level or intake of specific meat mutagens or heme iron and lung cancer risk.