Bladder cancer mortality trends and patterns in Cordoba, Argentina (1986-2006)

Background Bladder cancer is common worldwide and the fourth most commonly diagnosed malignancy in men in Argentina. Objective To describe bladder cancer mortality trends in Cordoba (1986-2006), considering the effect of age, period, and cohort, and to estimate the effect of arsenic exposure on bladder cancer, and its interaction with sex, while controlling by smoking habits and space and time variation of the rates. Methods A joinpoint regression was performed to compute the estimated annual percentage changes (EAPC) of the age-standardized mortality rates (ASMR) in an adult population from Cordoba, Argentina. A Poisson model was fitted to estimate the effect of age, period, and cohort. The influence of gender, tobacco smoking (using lung cancer ASMR as surrogate), and arsenic in drinking water was examined using a hierarchical model. Results A favorable trend (1986-2006) in bladder cancer ASMR in both sexes was found: EAPC of -2.54 in men and -1.69 in women. There was a decreasing trend in relative risk (RR) for cohorts born in 1931 or after. The multilevel model showed an increasing risk for each increase in lung cancer ASMR unit (RR = 1.001) and a biological interaction between sex and arsenic exposure. RR was higher among men exposed to increasing As-exposure categories (RR male low exposure 3.14, RR male intermediate exposure 4.03, RR male high exposure 4.71 versus female low exposure). A non-random space-time distribution of the rates was observed. Conclusions There has been a decreasing trend in ASMR for bladder cancer in Cordoba. This study confirms that bladder cancer is associated with age, gender, smoking habit, and exposure to arsenic. Moreover, an effect measure modification between exposure to arsenic and sex was found.