title: Survival analysis of patients with interval cancer undergoing gastric cancer screening by endoscopy.
abstract: OBJECTIVE
  Interval cancer is a key factor that influences the effectiveness of a cancer screening program. To evaluate the impact of interval cancer on the effectiveness of endoscopic screening, the survival rates of patients with interval cancer were analyzed.
  
  
  METHODS
  We performed gastric cancer-specific and all-causes survival analyses of patients with screen-detected cancer and patients with interval cancer in the endoscopic screening group and radiographic screening group using the Kaplan-Meier method. Since the screening interval was 1 year, interval cancer was defined as gastric cancer detected within 1 year after a negative result. A Cox proportional hazards model was used to investigate the risk factors associated with gastric cancer-specific and all-causes death.
  
  
  RESULTS
  A total of 1,493 gastric cancer patients (endoscopic screening group: n = 347; radiographic screening group: n = 166; outpatient group: n = 980) were identified from the Tottori Cancer Registry from 2001 to 2008. The gastric cancer-specific survival rates were higher in the endoscopic screening group than in the radiographic screening group and the outpatients group. In the endoscopic screening group, the gastric cancer-specific survival rate of the patients with screen-detected cancer and the patients with interval cancer were nearly equal (P = 0.869). In the radiographic screening group, the gastric cancer-specific survival rate of the patients with screen-detected cancer was higher than that of the patients with interval cancer (P = 0.009). For gastric cancer-specific death, the hazard ratio of interval cancer in the endoscopic screening group was 0.216 for gastric cancer death (95%CI: 0.054-0.868) compared with the outpatient group.
  
  
  CONCLUSIONS
  The survival rate and the risk of gastric cancer death among the patients with screen-detected cancer and patients with interval cancer were not significantly different in the annual endoscopic screening. These results suggest the potential of endoscopic screening in reducing mortality from gastric cancer.
authors.affiliation: Cancer Screening Assessment and Management Division, Research Center for Cancer Prevention and Screening, National Cancer Center, Tokyo, Japan.
authors.forename: Chisato
authors.initials: C
authors.lastname: Hamashima
authors.affiliation: Department of Internal Medicine, San-in Rosai Hospital, Yonago, Tottori Prefecture, Japan.
authors.forename: Michiko
authors.initials: M
authors.lastname: Shabana
authors.affiliation: Division of Environmental and Preventive Medicine, Department of Social Medicine, Faculty of Medicine, Tottori University, Yonago, Tottori Prefecture, Japan.
authors.forename: Mikizo
authors.initials: M
authors.lastname: Okamoto
authors.affiliation: Division of Environmental and Preventive Medicine, Department of Social Medicine, Faculty of Medicine, Tottori University, Yonago, Tottori Prefecture, Japan.
authors.forename: Yoneatsu
authors.initials: Y
authors.lastname: Osaki
authors.affiliation: Division of Environmental and Preventive Medicine, Department of Social Medicine, Faculty of Medicine, Tottori University, Yonago, Tottori Prefecture, Japan.
authors.forename: Takuji
authors.initials: T
authors.lastname: Kishimoto
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D055088:Early Detection of Cancer; D004724:Endoscopy; D005260:Female; D006801:Humans; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D016016:Proportional Hazards Models; D013274:Stomach Neoplasms / Q000175:diagnosis / Q000401:mortality*; D016019:Survival Analysis