Epidemiology of gastrointestinal and liver cancers in the Asian Pacific region

Gastric cancer (GCA) has long being thought be an Asian type of cancer and broadly associated with poverty whereas colorectal cancer (CRC) has been thought to be a Western type of cancer associated with affluence. The incidence of GCA ha declined dramatically in the West, in very high incidence countries of East Asia, the age standardized incidence rates (ASR) have also declined. However with an aging population, the absolute number of cases of GCA in Asia will increase rather than decrease. The decrease in GCA is associated with the decrease in the prevalence of HP which ironically had started to decline even before its discovery. The discrepancy between high HP prevalence and low GCA incidence is seen chiefly amongst Southern Asians of Indian origin and has been aptly termed the Indian enigma. CRC is a new emerging cancer in the region. Some of the highest CRC ASR rates have been reported from Asian countries. In many Asian countries, the ASR of GCR has now surpassed that of GCA. Hepatocelluar carcinoma (HCC) is also an important cnacer in the Asian Pacific region. The highest ASR in the world are reported from Asian countries of Mongolia, Korea and Japan. The underlying etiology across the region has been the highly prevalence hepatitis B infection except in Japan where hepatitis C is an important cause of HCC. With population mass vaccination of hepatitis B at birth in many countries and markedly improved public health measures, viral hepatitis B and C are set to decline with time. However, the exponential increase in obesity and non-alcoholic fatty liver portends a future epidemic of fatty liver-related HCC.