Tar, nicotine and carbon monoxide yield of UK cigarettes and the risk of non-muscle-invasive and muscle-invasive bladder cancer

Cigarette smoking is a major risk factor for bladder cancer (BC); however, the impact of cigarette content remains unclear. This study aims to investigate tar, nicotine and carbon monoxide (TNCO) yields of different filtered cigarettes in relation to BC risk. From the Bladder Cancer Prognosis Programme 575 non-muscle-invasive bladder cancer (NMIBC) cases, 139 muscle-invasive bladder cancer (MIBC) cases and 130 BC-free controls with retrospective data on smoking behaviour and cigarette brand were identified. Independently measured TNCO yields of cigarettes sold in the UK were obtained through the UK Department of Health and merged with the Bladder Cancer Prognosis Programme dataset to estimate the daily intake of TNCO. BC risk increased by TNCO intake category for NMIBC cases (P <0.050 in all multivariate models), but only for the daily intake of tar for MIBC cases (P=0.046) in multivariate models. No difference in risk was observed between smokers of low-tar/low-nicotine and high-tar/high-nicotine cigarettes compared with never smokers, either for NMIBC (P=0.544) or MIBC (P=0.449). High daily intake of TNCO additionally increases the risk of both NMIBC and MIBC compared with low daily intake. However, as there is no difference in BC risk between low-tar/low-nicotine and high-tar/high-nicotine cigarette smokers, it remains unclear whether smoking behaviour or TNCO yield of cigarettes explains this association.