醫院乳癌監測的效果分析

Abstract

目的：本研究為醫院乳癌監測－定期乳房攝影與超音波檢查－的效果評估；過去乳癌篩檢的研究都是以群眾為主的對照試驗，這與醫院進行的乳癌監測是截然不同的。 材料和方法：我們使用某癌症防治中心民國87年到91年的癌症登記檔來確認841名乳癌病人。行政資料提供病人是否曾在醫院監測的經歷。同時期曾在同醫院接受乳房影像學檢查且非乳癌者為健康對照組。全監測族群以年齡分層（大等於五十歲相對於小於五十歲）並使用二元應變項logistic迴歸模型分析。乳癌病人次族群分析乳癌確診時的臨床病理特徵包含：腫瘤大小（大等於或小於兩公分）、腋下淋巴節狀態（有或沒有移轉）及組織學特徵（侵犯性癌或原位癌）。這些替代性終點由追蹤期的乳癌復發與存活分析得到證實（log-rank檢定：p值分別為<0.0001與0.0343）。多階離散狀態時間同質性馬可夫模型進一步分析組織學特徵的研究終點；並探討乳癌監測是否能減緩狀態移轉速率。 結果： 全族群分析顯示對停經前婦女（小於五十歲）單獨進行乳房超音波檢查而非乳房攝影或超音波�攝影合併檢查辨識出較多乳房良性狀態而非癌症。此效果對年長女性（大等於五十歲）較不顯著，且僅限於前一至兩年的超音波檢查發現（得乳癌勝算比：0.179，p值為0.0041）。癌症病人次族群分析顯示乳癌發病前一至兩年單獨乳房攝影對乳癌組織學型態的研究終點有保護效果（年齡調整後得侵犯性癌勝算比：0.048，p值為0.016）。三階段馬可夫模型顯示監測的淨效益為66.18%（63.44~72.10%）；發病前兩年監測使原位癌到侵犯性癌的移轉速率下降65.16%（59.79~76.74%）。 結論：本研究強調醫院乳癌監測的異質本質。與乳房攝影相比，超音波偵測到更多的良性狀況。單獨乳房攝影做為乳癌篩檢的黃金標準得到確認。未來研究仍需對醫院乳癌監測的本質和成效做進一步的闡明。

Purpose: To evaluate effectiveness of hospital-based breast cancer surveillance with periodic mammography/ultrasonography examinations; previous breast cancer screening study was conducted on population-based randomized trials, which was distinct from breast cancer surveillance at hospitals. Materials and methods: We used cancer registry file from one cancer prevention center between 1998 and 2004 to ascertain 841 breast cancer cases. Surveillance history was obtained through administration data. Healthy controls were those undergoing breast image examinations and were free of cancer at the same institute concurrently. The whole breast surveillance cohort was analyzed using logistic regression model stratified by age group (>50 versus <50 years) with dichotomous responses. Subgroup analysis of cancer patients were targeted for clinical and pathological features during diagnosis of breast cancer; including tumor size (>2cm versus <2cm), axillary lymph node status (presence versus absent), and histological behavior (invasive cancer versus carcinoma in situ). These surrogate endpoints were validated from disease-free survival and mortality during follow-up (log-rank test: p<0.001 and p=0.0343, respectively). Discrete states time homogenous Markov model was applied to histological behavior; effects of surveillance as transitional parameters reduction were surveyed. Results: Whole cohort analysis showed that for pre-menopause women (age<50 years), ultrasonograophy alone, rather than mammography or two modalities combined, recognized more benign breast conditions than cancer. The effect was less prominent for older women (age>50 years) and was only observed during the preceding one to two years (odds ratio of breast cancer: 0.179, p=0.0041). Subgroup analysis of breast cancer patients showed that mammography alone between one to two years before cancer diagnosis had protective effect upon histological behavior (age-adjusted odds ratio of invasive cancer: 0.048, p=0.016). Three states Markov model showed net efficacy of surveillance was 66.18% (63.44~72.10%); surveillance within 2 years of disease onset resulted in 65.16% (59.79~76.74%) reduction of carcinoma in situ to invasive cancer transition. Conclusion: Current study highlighted hybrid nature of hospital-based breast cancer surveillance. Compared with mammography, ultrasonography detected more benign breast conditions. Mammography alone remains as gold standard for breast cancer screening. Further study to elucidate the nature and performance of hospital-based breast cancer surveillance is warranted.