(1) Background: Screen-detected breast cancer patients tend to have better survival than patients diagnosed with symptomatic cancer. The main driver of improved survival in screen-detected cancer is detection at earlier stage. An important bias is introduced by lead time, i.e., the time span by which the diagnosis has been advanced by screening. We examine whether there is a remaining survival difference that could be attributable to mode of detection, for example, because of higher quality of care. (2) Methods: Women with a breast cancer (BC) diagnosis in 2000–2022 were included from a population-based cancer registry from Schleswig-Holstein, Germany, which also registers the mode of cancer detection. Mammography screening was available from 2005 onwards. We compared the survival for BC detected by screening with symptomatic BC detection using Kaplan–Meier, unadjusted Cox regressions, and Cox regressions adjusted for age, grading, and UICC stage. Correction for lead time bias was carried out by assuming an exponential distribution of the period during which the tumor is asymptomatic but screen-detectable (sojourn time). We used a common estimate and two recently published estimates of sojourn times. (3) Results: The analysis included 32,169 women. Survival for symptomatic BC was lower than for screen-detected BC (hazard ratio (HR): 0.23, 95% confidence interval (CI): 0.21–0.25). Adjustment for prognostic factors and lead time bias with the commonly used sojourn time resulted in an HR of 0.84 (CI: 0.75–0.94). Using different sojourn times resulted in an HR of 0.73 to 0.90. (4) Conclusions: Survival for symptomatic BC was only one quarter of screen-detected tumors, which is obviously biased. After adjustment for lead-time bias and prognostic variables, including UICC stage, survival was 27% to 10% better for screen-detected BC, which might be attributed to BC screening. Although this result fits quite well with published results for other countries with BC screening, further sources for residual confounding (e.g., self-selection) cannot be ruled out.
（1）背景：通过筛查发现的乳腺癌患者往往比有症状确诊的患者具有更好的生存率。筛查发现癌症生存改善的主要驱动因素是早期发现。领先时间偏倚（即筛查使诊断提前的时间跨度）会引入重要偏差。本研究旨在探讨是否存在可归因于检测模式（例如更高质量的医疗照护）的剩余生存差异。（2）方法：从德国石勒苏益格-荷尔斯泰因州基于人群的癌症登记处纳入2000-2022年确诊的乳腺癌女性患者，该登记系统同时记录癌症检测模式。乳腺X线筛查自2005年开始实施。我们采用Kaplan-Meier法、未调整的Cox回归以及调整年龄、分级和UICC分期的Cox回归，比较筛查检出与症状性检出乳腺癌的生存差异。通过假设肿瘤处于无症状但可筛查检测期（停留时间）呈指数分布，对领先时间偏倚进行校正。我们采用了一个常用估计值和两个近期发表的停留时间估计值。（3）结果：分析共纳入32,169名女性。症状性乳腺癌的生存率低于筛查检出的乳腺癌（风险比（HR）：0.23，95%置信区间（CI）：0.21-0.25）。使用常用停留时间对预后因素和领先时间偏倚进行调整后，HR为0.84（CI：0.75-0.94）。采用不同停留时间估计值得出的HR范围为0.73至0.90。（4）结论：症状性乳腺癌的生存率仅为筛查检出肿瘤的四分之一，这显然存在偏倚。在调整领先时间偏倚及包括UICC分期在内的预后变量后，筛查检出乳腺癌的生存优势仍保持27%至10%，这可能归因于乳腺癌筛查。尽管该结果与其他开展乳腺癌筛查国家已发表的研究高度吻合，但仍不能排除残余混杂因素（如自我选择偏倚）的其他来源。
Lead-Time Corrected Effect on Breast Cancer Survival in Germany by Mode of Detection
肿瘤(癌症)患者之家