Air pollution and incident bladder cancer: A risk assessment

Abstract

Dear editor, I have read with interest the article entitled "Ambient air pollution and incident bladder cancer risk: Updated analysis of the Spanish Bladder Cancer Study" by Turner et al. 1 that evaluated the association between ambient particulate matter within a diameter of 2.5 (PM2.5), nitrogen dioxide (NO 2 ) and bladder cancer incidence. Although there were no significant associations of ambient PM2.5 and NO 2 concentrations with incident bladder cancer, some cautions should be paid to the methodology of their research.First, the authors adopted single pollutant and two pollutant models by using estimation data from residential areas and a dependent variable was personal information on incident bladder cancer. As there is a variation of ambient PM2.5 and NO 2 within the same study area, individual exposure levels of ambient PM 2.5 and NO 2 should be used instead of estimated values, although there are difficulties of measuring individual data.Second, the authors adopted unconditional logistic regression models for the analysis. I suppose that case-control matching data were canceled and conservative results would be derived by their statistical procedure. 2 Although there are some stronger factors than air pollutions for incident bladder cancer, conditional logistic regression models can be applied to case-control matching data.Finally, the authors cited a meta-analysis of cohort studies, presenting no significant association between air pollution and incident bladder cancer. The air pollution data were gathered by the same method, and I speculate that personal lifestyle factors would greatly contribute to the risk of bladder cancer. 3,4 Yours sincerely Tomoyuki Kawada References 1. Turner MC, Gracia-Lavedan E, Cirac M, et al. Ambient air pollution and incident bladder cancer risk: updated analysis of the Spanish bladder cancer study. Int J Cancer 2019;145:894-900. 2. Pedersen M, Stafoggia M, Weinmayr G, et al. Is there an association between ambient air pollution and bladder cancer incidence? Analysis of 15 European cohorts. Eur Urol Focus 2018;4:113-20. 3. Cumberbatch MGK, Jubber I, Black PC, et al. Epidemiology of bladder cancer: a systematic review and contemporary update of risk factors in 2018. Eur Urol 2018;74:784-95. 4. Kwan ML, Garren B, Nielsen ME, et al. Lifestyle and nutritional modifiable factors in the prevention and treatment of bladder cancer.