Trends in incidence of gallbladder cancer - Indian scenario

Background: Reports of increasing incidence rates of gallbladder cancer in several areas in India prompted the analysis of time trends. The present communication reports its geographic and gender distribution and trends in occurrence of this disease over time. Materials and methods: The data published in Cancer Incidence in Five Continents for various Indian registries for different periods and/or publication by the individual registries served as the source material. Mean annual percentage change (MAPC) in incidence rates was computed using relative difference between two time periods (earliest and latest), and estimation of annual percent change (EAPC) was computed by log-linear regression model. Results: In 1998–2006, incidence rates of gallbladder cancer (age-standardized rate, ASR) were high in Delhi and Kamrup ((3.6 and 7.4) and (5.3 and 14.3) per 105 person years in males and females, respectively) and lowest in Aurangabad, 0.0 in both genders. The incidence rate revealed an increase in all registries. MAPC in ASR ranged from 1.0% to 8.10%. EAPC for Mumbai, Chennai, and Bangalore for the period 1983–2002 revealed statistically significant increase in crude, age-standardized, and truncated rate (TR) (35–64 years) incidence rates. The largest EAPC in ASR was in Chennai (almost 6.0% in both genders) and smallest in Mumbai (3.5% and 2.1% in males and females, respectively). Conclusions: Statistically significant increase in gallbladder cancer incidence rates has been reported for Mumbai, Chennai, and Bangalore. Further studies are required in identifying factors that may be operative in etiology of cancer of gallbladder.