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

A Markov Chain Model to assess a multi-centered Screening Project for Breast Cancer in Taiwan

嚴明芳(Ming-Fang Yen) ； 陳秀熙(Tony Hsiu-Hsi Chen) ； 郭旭崧(Hsu-Sung Kuo) ； 賴美淑(Mei-Shu Lai) ； 張金堅(King-Jen Chang)

《中華公共衛生雜誌》 18卷2期 (1999/04) Pp. 95-104

https://doi.org/10.6288/CJPH1999-18-02-03

摘要

制定篩檢政策時，常面臨篩檢頻率究竟應該多長的問題。一般而言，疾病的臨床症前可偵測期(PCDP, Preclinical Detectable Phase)愈短、疾病病程愈快者，其篩檢頻率應該要愈頻繁。因此臨床症前期之平均長很重要之角色。本研究自1995年至1996年10月止利用台灣地區12家大型醫院，鎖定出2629名高危險群婦女接受乳癌篩檢，第一年篩檢到的31名病病例之實證資料，推估得婦女乳癌之臨床症前期發生率(preclinical incidence rate)為每年每千人5.7人（0.0057/年），依據這些資料。結果發現婦女乳癌臨床症前期平均長短約為1.90年(95% CI: 1.18-4.86)。根據乳癌之病理分期，第一期者由臨床症前期至臨床期約為8年，第二期及以上者則約為3個月。應用此結果模擬不同篩檢間隔之成效發現篩檢間隔個案(interval cases)之比例隨間隔增加而增加（1年間隔為22.8%；3年間隔為50%），病理分期第二期及以上者比例亦有比（3年間隔為6.45%；1年間隔為3.1%）。配合存活資料可得現行一年之篩檢間隔政策可以降低乳癌死亡率36%(RR=0.64，95% CI=0.32-0.97)。本研究所發展之馬可夫鏈模式(Markov chain model)亦可應用於缺乏篩檢間隔發現個案(interval cases)之其他篩檢計畫評估。

關鍵字

乳癌篩檢 ； 高危險群 ； 疾病自然史 ； 馬可夫鏈模式

並列摘要

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.

並列關鍵字

breast cancer screening ； high risk group ； natural history ； Markov chain model