The Role of Environmental Factors in Digestive Cancer

Abstract

The risk of digestive cancer in each country is analyzed in cancer registries for Incidence and Mortality. Survival is estimated from registries with a correct follow-up. Estimated values of Incidence and Mortality, expressed as an age standardized rate (ASR) for 100 000 persons, for all the population of a country are also found in the WHO-IARC database Globocan, recently edited for the year 2008. At each site of digestive tumors, the variations between countries, in cancer incidence, mortality and survival, depend on the resources and the global health status of the country. Indeed environmental causal factors linked to lifestyle may have an increasing or decreasing impact on the risk of cancer. Such factors are classified on 3 categories: 1- nutrition plays a determinant role in colorectal cancer with a higher risk in countries with more resources and more calories in the diet. 2- Toxic agents like alcohol and tobacco increase the risk at all sites of digestive cancer; their role is preponderant in esophageal cancer. Aflatoxin, a food contaminant in tropical, less developed countries, increases the risk of liver cancer. 3 – Infectious agents play a major role with the Bacteria H.pylori for stomach cancer over the world, and the Hepatitis virus B and C for liver cancer in less developed countries of Africa and Asia. The control of carcinogenic causal environmental factors is included in the primary prevention of digestive cancer.