Trends in rectal cancer incidence--Indian scenario

The objective was to analyse time trends of rectal cancer for the Indian population by gender, year of diagnosis, and age. Published data for Indian registries were obtained from "Cancer Incidence in Five Continents" and /or individual Indian registries for different time periods. Mean annual percentage change (MAPC) in incidence rates for seven Indian registries was computed using relative difference between two time periods (earliest and latest) and estimation of annual percentage change (EAPC) was computed for three registries by log-linear regression model using SAS version 8.1. The age standardized incidence rate (ASR) of rectal cancer during 2004-2006 ranged from 0.0 to 5.0 per 100,000 population with a male preponderance in most Indian registries. Among males, excepting for the Southern cities, all other registries revealed a decreasing trend/no change in the MAPC both in crude incidence rate (CR) and ASR. However, in females, an increase in MAPC in CR was noted in several registries. Statistically significant increase in EAPC in CR was observed in all the three registries ranging from 1.45% to 3.99% in males while in females the increase was 1.13% in Mumbai and 1.76% in Bangalore. Further studies are required to understand these changing trends and factors that operate in the aetiology of rectal cancer in the Indian scenario. Higher incidence in males indicates the need for greater attention to understand the causes of gender disparities.