time of occurrence and age distribution of digestive tract cancers in northern iran

background: previous studies indicate a high incidence of digestive cancers along southern parts of caspian sea including ma­zandaran province. the present study was conducted to further investigate time to occurrence, age distribution and pos­sible risks associated with the incidence time of digestive cancers in the above regions. methods: for this purpose the data of digestive cancer incidence of 3723 cases during a five-year period of 2001 to 2005 col­lected from babol cancer registry center in iran. almost all cancer cases residence of mazandaran province is included in this study and so the results could be considered a population-based conclusion. in order to modify the mortality due to other causes before digestive cancers, and to adjust the effect of digestive cancers correlations, a competing risks model was used. the cox regression model was used for study of risk factors on cancer incidence. results: although incidence of colorectal cancer was relatively low, however, unfortunately the age of onset was at the age cate­gory of 15-19, much sooner than occurrence of stomach cancer which was at 20-24 yr ( p < 0.0001), and esophageal can­cer at age category of 30-34 yr ( p < 0.0001). conclusion: life tables of all digestive cancer, esophageal cancer, stomach and colorectal cancers were presented in this pa­per. risks related to these cancers are significantly higher in men and residences of urban areas than their baseline coun­terparts. ( p < 0.0001) more studies needed to identify risk factors and high risk cases for screening and prevention programs.