Copyright © 2019 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. Research paper 1 0959-8278 Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved. DOI: 10.1097/CEJ.0000000000000531 Colorectal cancer risk factors in asymptomatic Chilean population: a survey of international collaboration between Japan and Chile Takuya Okada a,b , Tomoyuki Odagaki a , Francisco López-Köstner c , Alejandro J. Zárate c,d , Alejandra Ponce c , Udo Kronberg c , Stanko Karelovic e , Sergio Flores f , Ricardo Estela g , Takashi Ito a,h , Masamichi Yasuno a,b , Hiroyuki Uetake a,i , Kazuyuki Kojima j and Masanobu Kitagawa k In Chile, the mortality from colorectal cancer has been on the rise. A national screening program based on a fecal immunochemical test was started in 2012 as an international collaboration with Japan. This case- control study was designed to identify the risk factors for colorectal cancer, with a goal of increasing the participation rate for colorectal cancer screening. In accordance with the Strengthening the Reporting of Observational Studies in Epidemiology guidelines, we conducted a case-control study from 2012 to 2017; 23 845 asymptomatic participants were enrolled in the study. Participants who were fecal immunochemical test-positive or had a family history of colorectal cancer underwent a colonoscopy. We analyzed the odds ratio of the risk factors for colorectal cancer, including sex, age, family history, BMI, hypertension, diabetes, regular use of nonsteroidal anti-inflammatory drugs, alcohol consumption, smoking, physical activity, and daily intake of certain food items. For the screening program, 202 cases of colorectal cancer were detected, and 195 of them were evaluated pathologically after resection. Of these, 173 cases (88.7%) had colorectal cancer stage 0/1, 151 (77.4%) of which were treated with endoscopic resection. In the multivariate analysis, male sex, family history of colorectal cancer, and low intake of cereals or fibers were closely related to a high colorectal cancer incidence. Moreover, participants in their 60s and 70s had a higher incidence of colorectal cancer than those in their 50s. These results suggest that intensive screening of the high-risk population can help in improving the detection of colorectal cancer, whereas higher consumption of cereals or fibers can be effective in preventing its onset. European Journal of Cancer Prevention XXX:000–000 Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved. European Journal of Cancer Prevention 2019, XXX:000–000 Keywords: adenoma detection rate, Chile, colonoscopy, colorectal cancer, international collaboration, Latin America, risk factor, screening a Latin American Collaborative Research Center, Tokyo Medical and Dental University, Santiago, Chile, b Department of Gastrointestinal Surgery, Tokyo Medical and Dental University, Tokyo, Japan, c Unit of Coloproctology, Clinica Las Condes, d Department of Surgery, Finis Terrae University, Santiago, e Department of Digestive Endoscopy, Magallanes Hospital, Punta Arenas, f Department of Gastroenterology, Dr. Eduardo Pereira Hospital, Valparaiso, g Chilean-Japanese Institute for Digestive Diseases, San Borja Arriaran Hospital, Santiago, Chile, h Department of Human Pathology, Tokyo Medical and Dental University, i Department of Surgical Specialties, Tokyo Medical and Dental University, j Center for minimally Invasive surgery, Tokyo Medical and Dental University and k Department of Comprehensive Pathology, Tokyo Medical and Dental University, Tokyo, Japan Correspondence to Takuya Okada, Latin American Collaborative Research Center, Tokyo Medical and Dental University, Santiago, Chile Lo Fontecilla 441, Las Condes, Santiago 755-0000, Chile Tel: +56 2 610 3780; fax: +56 2 610 8610; e-mail: t-okada.srg1@tmd.ac.jp Received 4 April 2019 Accepted 27 June 2019 Introduction Colorectal cancer (CRC) is one of the most commonly diagnosed malignancies with 1.4 million new cases and more than 600 000 deaths per year worldwide (Ferlay et al., 2015). Its incidence and related mortality have been increasing in economically transitioning countries (Center et al., 2009), including those in Latin America (Bray and Piñeros, 2016). In Chile as well, mortality from CRC has increased rapidly over the past 15 years, mainly because of nutritional and lifestyle changes (Zarate et al., 2013). On the other hand, some epidemiological studies have reported that the development of CRC is related to risk factors such as alcohol, diet, and physical activity, and managing these risk factors could result in lower CRC incidence (Brenner et al., 2014). Furthermore, mass screening can help reduce the morbidity from CRC (Lynge, 2000; Strong et al., 2005). With this increase in incidence, prevention of CRC with a systematic screening system is now recognized as an urgent issue by the Chilean government and medical professionals. With their extensive history of interna- tional collaborations with the Tokyo Medical and Dental University (TMDU) of Tokyo, Japan, which began in 1968, the Ministry of Health of Chile decided to invite medical experts from TMDU to help establish a new