The researchers collected annual age-adjusted incidence rates for bladder cancer from the Surveillance, Epidemiology, and End Results (SEER) database between 1983 and 2013 and annual data on tobacco smoking between 1953 and 1983. The annual overall tobacco smoking prevalence rates were extracted from the Report of the Surgeon General and the Center for Disease Control between 1953 and 1983. During this period, tobacco smoking decreased from 37.9% to 32.1%, while the incidence rates for bladder cancer did not change significantly (45.6 to 45.5 per 100,000 person-years). The incidence rates for lung cancer decreased significantly from 146 to 122.9 per 100,000 person-years. In line with this, there was a significant association between the prevalence of tobacco smoking and the incidence of lung cancer. Exposure to tobacco smoking accounted for approximately 89.7% and 0.8% of the variation in lung and bladder cancer incidence rates, respectively.
Gender-specific analyses revealed that the prevalence of tobacco smoking decreased significantly among men (52.6% to 30%) but increased significantly among women (23.7% to 29%). In contrast, the age-adjusted incidence rates for bladder cancer decreased slightly but significantly among women but did not change significantly among men. The incidence rates for lung cancer significantly decreased among men but increased significantly among women. Among men, smoking accounted for 95.8% and 2.7% of lung and bladder cancer incidence rates, respectively. Among women, smoking accounted for 90.69% and 11.59% of lung and bladder cancer incidence rates, respectively.
These findings reveal a strong link between tobacco smoking and lung cancer incidence, with a weaker correlation with bladder cancer incidence. This indicates that other environmental and biological risk factors may be at play. Another potential explanation is that the composition of cigarettes has changed significantly, with a reduction in certain toxic compounds but increases in others. These may differentially impact bladder versus lung tumorigenesis. Limitations of this study include the use of separate data sources to collect data on smoking and cancer incidence, limiting insights into whether individual smokers developed lung or bladder cancer. The authors assumed a 30-year latency period between smoking exposure and the occurrence of bladder and lung cancer, potentially confounding the inferred links between variables. Finally, the authors point to other differences in the biology of lung and bladder cancers, including the high prevalence of APOBEC3-induced mutations in these patients.
Written by: Bishoy M. Faltas, MD, Director of Bladder Cancer Research, Englander Institute for Precision Medicine, Weill Cornell Medicine
Reference:
- Seisen T, Labban M, Lipsitz SR, Preston MA, Mossanen M, Bellmunt J, Rouprêt M, Choueiri TK, Kibel AS, Sun M, Trinh Q-D. Assessment of the Ecological Association between Tobacco Smoking Exposure and Bladder Cancer Incidence over the Past Half-Century in the United States. Current Oncology. 2023; 30(2):1986-1998.