Lifetime risk of urothelial carcinoma and lung cancer in the arseniasis-endemic area of Northeastern Taiwan

Arsenic in drinking water has been shown to increase the risk of urothelial carcinoma and lung cancer. However, the lifetime risk of developing urothelial carcinoma and lung cancer caused by exposure to arsenic in drinking water has not been reported. This study aimed to assess the lifetime risk of urothelial carcinoma and lung cancer caused by arsenic exposure from drinking water and cigarette smoking habit for residents living in the arseniasis-endemic area in Northeastern Taiwan. We recruited 8086 residents in 1991-1994 and monitored them for their newly developed types of cancers, identified by computerized linkage with the national cancer registry profile. There were 37 newly diagnosed urothelial carcinoma cases and 223 new lung cancer cases during the follow-up period (until 2007). The lifetime (35-85 years old) cumulative risk of developing urothelial carcinoma from an arsenic concentration in the drinking water of <10, 10-99, and 100+ μg/L was 0.29%, 1.07% and 3.43%, respectively. The corresponding probabilities were 7.42%, 8.99% and 17.09% for the lifetime risk of developing lung cancer. Cigarette smoking was associated with an increased risk of urothelial carcinoma and lung cancer, showing the hazard ratio (95% confidence interval) of 2.48 (1.27-4.82) and 3.44 (2.00-5.90) after adjusting for the arsenic concentration in drinking water. After adjusting for cigarette smoking, the hazard ratio (95% confidence interval) of developing urothelial carcinoma caused by the arsenic concentration in drinking water of <10, 10-99 and 100+ μg/L was 1.0 (the reference group), 2.18 (0.59-8.01), and 8.71 (2.49-30.48), respectively. The corresponding figures were 1.0 (the reference group), 1.14 (0.80-1.61), 1.84 (1.28-2.65) for lung cancer. Synergistic effects on the development of urothelial carcinoma and lung cancer existed between the arsenic exposure level and cigarette smoking. It is suggested that people who have had a high exposure to arsenic in drinking water should stop smoking cigarettes to lower their lifetime risk of urothelial carcinoma and lung cancer.