Asian Pacific Journal of Cancer Prevention, Vol 7, 2006 623 Trends in Stomach and Colorectal Cancer Incidences in Khon Kaen, Thailand Asian Pacific J Cancer Prev, 7, 623-626 RESEARCH COMMUNICATION Introduction Stomach and colorectal cancers are among the most common cancers in the world, with Japan currently having highest incidence rates for the colorectum worldwide and a continuing major problem with gastric cancer (Parkin et al., 2002). In Thailand, stomach and colorectal cancers are more common cancer in males more than females, the overall ratio for stomach cancers varying from 1.5 to 1.7 in Chiang Mai, Khon Kaen and Songkhla. The estimated age-standardized incidence rate was 4.9 per 100,000 for males and 3.0 per 100 000 for females. Chiang Mai had the highest incidence were 7.9 per 100 000 and 5.2 per 100,000 both males and Trends in Incidences of Stomach and Colorectal Cancer in Khon Kaen, Thailand 1985-2004 Krittika Suwanrungruang 1 , Surapon Wiangnon 2 , Supannee Sriamporn 3 , Aumkae Sookprasert 4 , Dhanes Rangsrikajee 5 , Supot Kamsa-ard 1 , Sujinant Horsith 1 , Pakanant Usantia 1 1 Cancer Unit, 2 Department of Pediatrics, Faculty of Medicine, 3 Department of Epidemiology, Faculty of Public Health, 4 Department of Medicine, Faculty of Medicine, 5 Department of Surgery, Faculty of Medicine, Khon Kaen University, Khon Kaen Thailand. *For Correspondence: Cancer Unit, Srinagarind hospital, Faculty of Medicine, Khon Kaen University, Khon Kaen 4002, Thailand.Tel & Fax: +66(0) 43-202485; E-mail: krisuw@kku.ac.th Abstract Backgr ound: The life styles of Thai people are changing with westernization and this would be expected to have an impact on the prevalence of cancer and other non-communicable diseases. For planning control programmes it is necessary to monitor change over time and the present study was conducted to provide information on stomach and colorectal cancer incidence rates in Khon Kaen Cancer Registry (KKCR), established in 1984 at the Faculty of Medicine, Srinagarind Hospital, Khon Kaen University. Objective: To assess trends in urban and rural areas of Khon Kaen province during 1985 - 2004. Methods: Data for stomach and colorectal cancer with an ICD-O diagnosis (coding C16 , C18 – C20) from the population-based cases of the KKCR, registered between 1985 and 2004, were retrieved and incidence trends were calculated using the Generalized Linear Model method (GLM), which generates incidence-rate-based logarithms. Results: The study population comprised 2,530 cases, 721 of stomach (males 449, females 272) and 1809 of colorectal (males 976, females 833) cancer. Most cases were aged 35-75 years. According to the histopathological diagnosis, the most common was adenocarcinoma with over 90 percent. The overall age- standardized incidence rates (ASR) for stomach cancer were 4.5 and 1.4 per 100 000 in males and females, respectively, during 1985-1989, 3.7 and 2.0 during 1990-1994, 3.0 and 2.2 during 1995-1999 and 3.6 and 1.8 during 2000-2004 . The respective figures for colorectal cancer were 3.3 and 2.6, 4.6 and 3.1, 5.4 and 3.5 and finally 5.8 and 5.3. In both urban and rural areas males were affected more frequently than females, although a shift was evident towards decrease in the se ratio was evident for colorectal cancers over time. Discussion: The results of this study showed slight increase in the incidence of colorectal cancer in Khon Kaen province, while rates for stomach cancer remained quite stable. The findings indicate a need for continuing research in stomach and colorectal cancer epidemiology, with subdivision into particular sites within these two sections of the gut. Key Words: Stomach and colorectal - incidence - trends - cancer registry females followed by Lampang ASR 7.5 and 4.6 per 100 000 in males and females. The lowest rates are in Songkhla ASR 2.0 and 1.4 per 100 000 in males and females respectively (Sriplung et al., 2003). The incidence rates for colorectal cancers in both sexes in Bangkok are higher than in the other regions in Thailand (Sriplung et al.,2005; Sriplung et al 2006). This reflects differences in life styles of Thai people within the different regions and variation in the rate of change to a western style diet, with higher fat, animal protein, low fiber and high levels of saturated fat (Ratnali et al, 2005 ; Sriamporn et al.,2005). Information on trends regarding prevalence of disease are clearly necessary for control planning. Since the Khon