Study design and patient recruitment for the Japan Polyp Study

Abstract

Yasushi Sano,1,2 Takahiro Fujii,3,4 Takahisa Matsuda,3 Yasushi Oda,5,6 Shin'ei Kudo,7 Masahiro Igarashi,8 Hiroyasu Iishi,9 Kazuhiro Kaneko,1,10 Kinichi Hotta,3,11,12 Nozomu Kobayashi,3,13 Yuichiro Yamaguchi,12 Kiyonori Kobayashi,8 Hideki Ishikawa,14 Yoshitaka Murakami,15 Tadakazu Shimoda,16 Takahiro Fujimori,17 Yoichi Ajioka,18 Hirokazu Taniguchi,16 Hiroaki Ikematsu,1,3 Kazuo Konishi,10 Yutaka Saito,3 Shigeaki Yoshida1,19 1Department of Gastroenterology, Endoscopy Division, National Cancer Center Hospital East, Kashiwa, 2Gastrointestinal Center and Institute of Minimally Invasive Endoscopic Care (iMEC), Sano Hospital, Kobe, 3Endoscopy Division, National Cancer Center Hospital, Tokyo, 4Takahiro Fujii Clinic, Tokyo, 5Hattori GI Endoscopy and Gastroenterology Clinic, Kumamoto, 6Oda GI Endoscopy and Gastroenterology Clinic, Kumamoto, 7Digestive Disease Center, Showa University Northern Yokohama Hospital, Yokohama, 8Department of Gastroenterology, Kitasato University East Hospital, Sagamihara, 9Department of Gastrointestinal Oncology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Osaka, 10Division of Gastroenterology, Department of Medicine, Showa University School of Medicine, Tokyo, 11Department of Gastroenterology, Saku Central Hospital, Saku, 12Division of Endoscopy, Shizuoka Cancer Center, Mishima, 13Department of Diagnostic Imaging, Tochigi Cancer Center, Utsunomiya, 14Department of Molecular-Targeting Cancer Prevention, Graduate School of Medical Science, Kyoto Prefectural University of Medicine, Kyoto, 15Department of Medical Statistics, Shiga University of Medical Science, Otsu, 16Pathology and Clinical Laboratory Division, National Cancer Center Hospital, Tokyo, 17Department of Surgical and Molecular Pathology, Dokkyo Medical University School of Medicine, Mibu, 18Division of Molecular and Diagnostic Pathology, Niigata University Graduate School of Medical and Dental Sciences, Niigata, 19Aomori Prefectural Hospital, Aomori, Japan Background: The Japan Polyp Study (JPS) Workgroup was established in 2000 to evaluate colonoscopic follow-up surveillance strategies. The JPS was a multicenter randomized controlled trial designed to evaluate follow-up surveillance strategies in patients who had undergone two complete colonoscopies for control of colorectal cancer, with removal of all detected polyps. The aim of the present analysis was to assess the patient recruitment and whether the clinical characteristics were adequate for enrollment at the participating centers. Materials and methods: Among referrals for colonoscopy at the eleven participating centers, all patients who were 40–69 years old, without a family or personal history of familial polyposis, Lynch syndrome, inflammatory bowel disease, or a personal history of polypectomy with unknown histology, and had no invasive colorectal cancer or colectomy, were considered for inclusion from February 2003. Results: Among 4,752 referrals, a total of 3,926 patients with a mean age of 57.3 (range 40–69) years, including 2,440 (62%) males, were included in the JPS. The participation rate was 83%. Among them, a total of 2,757 patients who had undergone two complete colonoscopies with removal of all detected polyps were eligible, giving an eligibility rate of 70% (2,757 of 3,926). Among the eligible patients, 2,166 were assigned to randomized groups, and 591 patients to a nonrandomized group. The last steps of data lock, analysis, and complete histopathological assessment based on a pathology review are ongoing. Conclusion: Eligible patients recruited for the JPS were successfully assigned on the basis of the expected sample-size calculation. Keywords: colonoscopy, follow-up surveillance strategies, Japan Polyp Study (JPS), study design, multicenter randomized controlled trial