Trends in the incidence of bladder cancer in Nova Scotia: a twenty-year perspective.

INTRODUCTION

Bladder cancer is the most common malignant tumor of the urinary system. Tobacco smoking has been implicated as a major risk factor for the development of bladder cancer and Nova Scotia has some of the highest smoking rates in Canada. We examined trends in the incidence of bladder cancer in Nova Scotia between 1980 and 1999.

MATERIALS AND METHODS

Data on incident cases of bladder cancer diagnosed in Nova Scotia over a twenty-year period (1980 - 1999) were obtained from the Nova Scotia Cancer Registry. The age- standardized incidence and mortality due to bladder cancer was calculated for both genders. Trends in the incidence of bladder cancer during the study period were analyzed for three different age groups in each gender as an estimate of birth cohort. The average annual percent change (AAPC) in incidence of bladder cancer was calculated.

RESULTS

Between 1980 and 1999, 3569 cases of bladder cancer were reported (male: female = 2.9:1). The overall incidence of bladder cancer increased in both males (27.5 to 39.5 cases per 100 000) and females (7.0 to 10.7 cases per 100 000). Mortality rates were stable. There was a trend towards an increase in bladder cancer rates for all age groups analyzed, with a substantial rise occurring in females less than 65 years of age. The AAPC in incidence of bladder cancer was +1.5 for males and +2.6 for females.

CONCLUSIONS

We hypothesize that the rising incidence of bladder cancer in Nova Scotia, particularly in individuals less than 65 years of age, is related to changes in cigarette smoking practices during the past century. As the population ages, we are likely to see an increased incidence of bladder cancer in females.