title: Mean sojourn time of preclinical gastric cancer in Korean men: a retrospective observational study.
abstract: OBJECTIVE
  This retrospective cohort study aimed to estimate the mean sojourn time (MST) of preclinical gastric cancer in Korean men.
  
  
  METHODS
  The subjects consisted of voluntary male screenees aged 40 to 69 years who underwent subsequent screening gastroscopies after testing negative at a baseline screening performed between January 2007 and December 2011. A new case was defined if gastric cancer cells were present in the biopsy specimens obtained from gastroscopy. The follow-up period was calculated as the number of person-years between the date of baseline screening gastroscopy and positive findings at a subsequent screening. The MST was calculated using transition rates of gastric cancer to determine the best screening interval.
  
  
  RESULTS
  Of the 171 979 voluntary male screenees, 61 688 (36%) underwent subsequent screening gastroscopies between January 2007 and December 2011. A total of 91 incident cases were found during 19 598 598 person-years of follow-up. The MST of gastric cancer was 2.37 years (95% confidence intervals, 1.92 to 2.96), and those aged 40 to 49 years had a shorter MST than those 50 to 69 years did.
  
  
  CONCLUSIONS
  These findings support the 2-year interval of screening recommended by the nationwide gastric cancer screening program in Korea. Further studies for the age-specific MST among women are needed.
  
  
  
  This retrospective cohort study aimed to estimate the mean sojourn time (MST) of preclinical gastric cancer in Korean men.
  
  
  
  The subjects consisted of voluntary male screenees aged 40 to 69 years who underwent subsequent screening gastroscopies after testing negative at a baseline screening performed between January 2007 and December 2011. A new case was defined if gastric cancer cells were present in the biopsy specimens obtained from gastroscopy. The follow-up period was calculated as the number of person-years between the date of baseline screening gastroscopy and positive findings at a subsequent screening. The MST was calculated using transition rates of gastric cancer to determine the best screening interval.
  
  
  
  Of the 171 979 voluntary male screenees, 61 688 (36%) underwent subsequent screening gastroscopies between January 2007 and December 2011. A total of 91 incident cases were found during 19 598 598 person-years of follow-up. The MST of gastric cancer was 2.37 years (95% confidence intervals, 1.92 to 2.96), and those aged 40 to 49 years had a shorter MST than those 50 to 69 years did.
  
  
  
  These findings support the 2-year interval of screening recommended by the nationwide gastric cancer screening program in Korea. Further studies for the age-specific MST among women are needed.
authors.affiliation: Department of Preventive Medicine, Jeju National University School of Medicine, Jeju, Korea.
authors.forename: Jong-Myon
authors.initials: JM
authors.lastname: Bae
authors.affiliation: Korea Medical Institute, Seoul, Korea.
authors.forename: Sang Yop
authors.initials: SY
authors.lastname: Shin
authors.affiliation: Department of Preventive Medicine, Jeju National University School of Medicine, Jeju, Korea.
authors.forename: Eun Hee
authors.initials: EH
authors.lastname: Kim
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D044466:Asian People; D015331:Cohort Studies; D055088:Early Detection of Cancer; D005773:Gastroscopy; D006801:Humans; D015994:Incidence; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D056910:Republic of Korea; D012189:Retrospective Studies; D013274:Stomach Neoplasms / Q000453:epidemiology* / Q000473:pathology; D013997:Time Factors
keywords: Early detection of cancer; Gastrointestinal endoscopy; Gastroscopy; Korea; Mass screening; Stomach neoplasms