A Markov chain model to assess a multi-centered screening project for breast cancer in Taiwan

M. F. Yen, H. H.T. Chen, H. S. Kuo, M. S. Lai, K. J. Chang

Research output: Contribution to journalArticlepeer-review


The optimal screening frequency is highly dependent on the duration of pre-clinical detectable phase (PCDP, also called sojourn time). This parameter is difficult to estimate partly because the progression from PCDP to clinical phase is unobservable and partly because data on interval cases is hardly available from screening project. To tackle these problems, 2629 women of high risk group aged 35 and above identified until October 1996 from 12 large hospitals in Taiwan received their first screening exams, and 31 individuals were detected with breast cancer. Among 575 women who had returned for the second year screening exam, three persons were found with positive results. The progress intervals between stages of the disease were estimated using left-censored and interval-censored Markov chain models with a 6-year follow-up simulation. Results showed an annual preclinical incidence rate of 5.7 per 1000 for the high-risk group. The mean sojourn time (MST) was 1.90 years (95% CI = 1.18-4.86). The proportion of interval case increased with the screening interval. A similar situation was also observed for the proportion of stage II+. Applying the Swedish Two-County trial experience, the one-year screening regimen would be able to reduce the mortality from breast cancers for 36% (RR = 0.64, 95% CI = 0.32-0.97). The breast cancer screening policy for high risk group initiated by department of health is justified by a high pre-clinical incidence rate estimated in this study. According to the estimated MST and the relationship between screening interval and the proportion of both interval case and mortality reduction, it is advisable that the screening interval for this high-risk group be no longer than two years. Finally, a left-censored and interval-censored Markov chain developed in this study could be applied to other screening projects short of data on interval cases.

Translated title of the contribution利用馬可夫鏈模式評估臺灣地區多中心乳癌高危險群篩檢計畫
Original languageEnglish
Pages (from-to)95-104
Number of pages10
JournalChinese Journal of Public Health
Issue number2
Publication statusPublished - 1999
Externally publishedYes


  • Breast cancer screening
  • High risk group
  • Markov chain model
  • Natural history

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health


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