Seely Jean M, Eby Peter R, Gordon Paula B, Appavoo Shushiela, Yaffe Martin J
University of Ottawa, Department of Radiology, Ottawa, ON, Canada.
The Ottawa Hospital, Ottawa Hospital Research Institute, Ottawa, ON, Canada.
J Breast Imaging. 2022 Apr 15;4(2):135-143. doi: 10.1093/jbi/wbac009.
To investigate why the Canadian National Breast Screening Study (CNBSS) did not show mortality reduction with mammography. This study explored long-standing concerns related to the validity of the randomization process, methods of recruiting women to participate in the trials, and training of the staff working in the CNBSS.
Surviving former CNBSS personnel, whose roles involved direct recruitment, enrollment, randomization, clinical examination, image interpretation, and management of patients in the CNBSS were interviewed. Individuals were contacted and consented to provide firsthand accounts of daily operations and adherence to research protocols via standardized questions. Consistency of observational data with quantitative results from the CNBSS trials was evaluated.
Eleven of 28 (39.3%) staff confirmed that women with preexisting symptoms of breast cancer were systematically recruited at some centers; 57.1% (16/28) confirmed that personnel performing screening in CNBSS had very limited training and experience; 39.3% (11/28) verified that imaging equipment was often substandard; 50% (14/28) indicated that mammography image quality was generally poor; and 28.6% (8/28) corroborated that in some cases surgeons were unwilling to perform biopsies or surgeries for women with suspicious abnormalities found only on screening mammography that lacked a palpable correlate.
These firsthand accounts provide new information confirming that the CNBSS did not consistently and rigorously assess the true efficacy of screening mammography. The staff accounts clarify reasons why the CNBSS results were outliers compared with the six other randomized trials of screening mammography and should not be used as credible scientific evidence to inform health policy.
调查为何加拿大国家乳腺筛查研究（CNBSS）未显示出乳腺钼靶检查可降低死亡率。本研究探讨了长期以来与随机分组过程的有效性、招募女性参与试验的方法以及CNBSS工作人员培训相关的问题。
对仍在世的曾参与CNBSS且其职责涉及直接招募、登记、随机分组、临床检查、影像解读及患者管理的人员进行访谈。通过标准化问题联系并征得这些人员同意，让他们提供关于日常操作及遵循研究方案情况的第一手描述。评估观察性数据与CNBSS试验定量结果的一致性。
28名工作人员中有11名（39.3%）证实，部分中心系统性地招募了已有乳腺癌症状的女性；57.1%（16/28）证实，在CNBSS中进行筛查的人员培训和经验非常有限；39.3%（11/28）证实，成像设备常常不合标准；50%（14/28）表示，乳腺钼靶图像质量总体较差；28.6%（8/28）证实，在某些情况下，外科医生不愿为仅在筛查乳腺钼靶中发现可疑异常但无可触及对应物的女性进行活检或手术。
这些第一手描述提供了新信息，证实CNBSS并未始终如一地严格评估筛查乳腺钼靶的真正疗效。工作人员的描述阐明了为何CNBSS的结果与其他六项乳腺钼靶筛查随机试验相比是异常值，且不应将其用作指导卫生政策的可靠科学证据。
