Time of Occurrence and Age Distribution of Digestive Tract Cancers in Northern Iran

Abstract

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.

Keywords

• Competing risks model
• Digestive cancers
• UN west life table model