乳房主要由乳腺组织和脂肪组织构成：脂肪组织比例越高，越透光，X光检查显示越黑；乳腺组织纤维比例越高，越不透光，X光检查显示越白。因此，根据X光检查结果，乳房可以分为脂肪型、散在纤维腺体型、不均匀致密型、极度致密型。如果年龄相似、乳房大小相似，其他风险因素相似，那么乳腺越致密，乳腺癌风险自然越高。而且，乳腺癌X光检查显示也是白的，要在大量显示为白色的致密乳腺组织中找出某个白点，这情况经常被形容为在多云的天空中寻找一朵白云。这时，就需要补充影像检查，目前主要包括：注射造影剂前后对比增强X光检查、快速磁共振成像、自动化全乳房超声。这三种方法各有优缺点，此前尚不明确哪种补充影像检查对乳腺癌筛查发现致密型乳房女性获益最大。

　　2025年5月21日，国际四大医学期刊之首、创刊于1823年的英国《柳叶刀》正刊在线发表英国剑桥大学、曼彻斯特大学医院、切尔滕纳姆和格洛斯特郡医院、利兹大学医院、伦敦大学皇家免费医院、诺丁汉大学医院、格拉斯哥大学医院、伦敦圣巴塞洛缪医院、莱斯特大学医院、邓迪大学医院、伦敦大学玛丽王后学院、美国西达赛奈医疗中心（黎巴嫩雪松医院和西奈山医院）联合起草的BRAID研究中期分析报告，对乳腺癌筛查发现致密型乳房女性三种补充影像检查方法（快速磁共振成像、自动化全乳房超声、增强X光检查）与标准方法复查（每隔三年数字化全乳房X光检查）进行比较。

BRAID (NCT04097366): Breast Screening – Risk Adaptive Imaging for Density

　　该多中心随机对照研究于2019年10月18日至2024年3月30日，从英国10个乳腺癌筛查中心入组9361例乳房X光检查结果阴性且为致密型的50至70岁女性，按批次（固定筛查中心或移动筛查车）独立随机分入四组：快速磁共振成像2318例、自动化全乳房超声2240例、增强X光检查2235例、标准方法复查2568例，具体取决于各个中心的检查方式。主要结局指标为乳腺癌检出率，定义为补充影像检查结果阳性且经组织学确诊为乳腺癌的女性百分比。根据收到的影像检查资料进行意向分析，采用网状荟萃分析对各个中心进行两项分析：一项分析仅对单用数字化全乳房X光检查后三个主动干预组（主要分析）比较三种补充影像检查技术的乳腺癌检出率、召回率和活检率；另一项分析增加剑桥大学单用数字化全乳房X光检查的观察数据。由于该研究已经结束招募，故本文进行中期分析（而非期中分析）。

　　结果，其中6305例完成补充影像检查：快速磁共振成像2130例、自动化全乳房超声2141例、增强X光检查2035例，并被纳入结局分析。

　　乳腺癌（包括导管原位癌和浸润癌）检出率：

  • 快速磁共振成像：17.4‰（95%置信区间：12.2～23.9，37例）

  • 自动化全乳房超声：4.2‰（95%置信区间：1.9～8.0，9例）

  • 增强X光检查：19.2‰（95%置信区间：13.7～26.1，39例）

　　乳腺浸润癌检出率：

  • 快速磁共振成像：15.0‰（95%置信区间：10.3～21.1，32例）

  • 自动化全乳房超声：4.2‰（95%置信区间：1.9～8.0，9例）

  • 增强X光检查：15.7‰（95%置信区间：10.8～22.1，32例）

　　快速磁共振成像乳腺癌检出率显著高于自动化全乳房超声（P=0.047），但是与增强X光检查相似（P=0.62）。

　　快速磁共振成像组发生造影剂外渗1例（0.5‰），自动化全乳房超声组未见不良事件；增强X光检查组发生碘造影剂反应24例（其中轻微17例、中度6例、重度1例，分别占8.4‰、2.9‰、0.5‰）、造影剂外渗3例（1.5‰）。

　　因此，该研究结果表明，快速磁共振成像和增强X光检查与自动化全乳房超声相比，虽然乳腺癌和乳腺浸润癌检出率高出三倍，但是肿瘤大小仅为一半。也就是说，前两种补充影像检查可以更早地发现致密型乳房女性的乳腺癌，但是可能造成过度诊断。

　　对此，澳大利亚悉尼大学发表同期评论：乳腺癌筛查发现致密型乳房后补充影像学检查正处于十字路口。

相关链接

Lancet. 2025 May 21. IF: 98.4

Comparison of supplemental breast cancer imaging techniques-interim results from the BRAID randomised controlled trial.

Gilbert FJ, Payne NR, Allajbeu I, Yit L, Vinnicombe S, Lyburn I, Sharma N, Teh W, James J, Seth A, Suaris T, Aggarwal R, Al-Attar M, Savaridas S, Antoniou A, Pharoah P, Duffy S.

University of Cambridge, Cambridge, UK; Manchester University NHS Foundation Trust, Manchester, UK; Cheltenham and Gloucestershire Hospital NHS Foundation Trust, Cheltenham, UK; Leeds Teaching Hospitals NHS Trust, Leeds, UK; Royal Free London NHS Foundation Trust, London, UK; Nottingham University Hospitals NHS Trust, Nottingham, UK; West of Scotland Breast Screening Services and Gartnavel General Hospital, Glasgow, UK; St Bartholomew’s NHS Hospital Trust, Lonodn, UK; University Hospitals of Leicester NHS Trust, Leicester, UK; University of Dundee, Ninewells Hospital NHS Tayside, Dundee, UK; Cedars-Sinai Hospital, Los Angeles, CA, USA; Queen Mary University of London, London, UK.

BACKGROUND: It is not known which supplemental imaging technique is most beneficial for women with dense breasts attending breast screening. This study compares abbreviated MRI, automated whole breast ultrasound (ABUS), and contrast-enhanced mammography versus standard of care in women with dense breasts and a negative mammogram. We report on interim results from the first round of supplemental imaging.

METHODS: In this UK randomised controlled trial, at ten breast screening sites, women (aged 50-70 years) were independently allocated by batches (day/mobile screening van) to either abbreviated MRI, ABUS, or contrast-enhanced mammography or standard of care (full-field digital mammography) varied by modality availability at each centre. Women were invited if their mammogram was negative and they had dense breasts. Primary outcome was detection rate, defined as the percentage of women with a positive result on supplemental imaging that resulted in histologically confirmed breast cancer. Analysis was by imaging received (intention to treat) using network meta-analysis, treating each site as a study in the meta-analysis, with two analyses carried out: one using only the three active intervention arms (primary analysis) that compared the three supplemental imaging techniques with respect to cancer detection, recall, and biopsy rates in addition to those resulting from full-field digital mammography alone; and one with the addition of the observational data from Cambridge on full-field digital mammography alone. This trial is closed for recruitment and is registered with ClinicalTrials.gov, NCT04097366.

FINDINGS: From October 18, 2019, to March 30, 2024, 9361 eligible women were recruited and randomly assigned (2318 to abbreviated MRI, 2240 to ABUS, 2235 to contrast-enhanced mammography, and 2568 to standard of care). Of those, 6305 completed supplementary imaging (2130 in the abbreviated MRI, 2141 in the ABUS, and 2035 in the contrast-enhanced mammography) and were included in the outcome analysis. The cancer detection rate was 17.4 (95% CI 12.2-23.9, n=37) per 1000 examinations for abbreviated MRI, 4.2 (1.9-8.0, n=9) per 1000 examinations for ABUS, and 19.2 (13.7-26.1, n=39) per 1000 examinations for contrast-enhanced mammography, of which 15.0 (10.3-21.1, n=32) per 1000 women for abbreviated MRI, 4.2 (1.9-8.0, n=9) per 1000 examinations for ABUS, and 15.7 (10.8-22.1, n=32) per 1000 examinations for contrast-enhanced mammography were invasive cancers. The detection rates for abbreviated MRI were significantly higher than for ABUS (p=0.047) and non-significantly higher than for contrast-enhanced mammography (p=0.62). There was one case of extravasation in the abbreviated MRI arm (0.5 events per 1000 examinations), no adverse events in the ABUS arm, and 24 iodinated contrast reactions (17 minor [8.4 events per 1000 examinations], six moderate [2.9 events per 1000 examinations], and one severe [0.5 events per 1000 examinations]) and three extravasations (1.5 extravasations per 1000 examinations) in the contrast-enhanced mammography arm.

INTERPRETATION: Abbreviated MRI and contrast-enhanced mammography detected three times as many invasive cancers compared with ABUS, with cancers being half the size. This study shows that supplemental imaging could lead to earlier detection of cancer in women with dense breasts but does not estimate the level of overdiagnosis.

FUNDING: Cancer Research UK, GE Healthcare, and Bayer Healthcare.

PMID: 40412427

DOI: 10.1016/S0140-6736(25)00582-3

Lancet. 2025 May 21. IF: 98.4

Breast cancer screening at a crossroads: supplemental imaging for dense breasts.

Houssami N.

The Daffodil Centre, the University of Sydney, a joint venture with Cancer Council, NSW, Australia; School of Public Health, Faculty of Medicine and Health, University of Sydney, NSW, Australia.

PMID: 40412424

DOI: 10.1016/S0140-6736(25)00803-7