Data and metadata supporting the published article: Contralateral breast cancer risk in patients with ductal carcinoma in situ and invasive breast cancer

In this study, the authors aimed to assess contralateral
breast cancer (CBC) risk in patients with ductal carcinoma in situ (DCIS)
compared to invasive breast cancer (BC).

Data access: The
datasets generated and/or analysed during the current study are not publicly
available, as the study has used external data from the Netherlands Cancer
Registry. The datasets will be made available from the Netherlands Cancer
Registry upon reasonable request (data request study number K18.245). To apply
for data access, please visit https://www.iknl.nl/en/ncr/apply-for-data.
The datasets that support figures 1 and 2, and supplementary figures 2-4, are
publicly available in the figshare repository, as part of this data record.

Study approval: The
NCR Privacy Review Board approved the proposal. Data were handled in accordance
with privacy regulations for medical research.

Study aims and
methodology: Contralateral breast cancer (CBC) is the most frequent second
cancer reported after first invasive breast cancer (BC). The cumulative
incidence of invasive CBC for women following invasive BC is ~0.4% per year.
Several studies have shown a decrease in CBC incidence as a result of
(neo)adjuvant systemic therapies. The aim of this study was to assess the risk
of developing invasive CBC in DCIS patients in direct comparison with patients
diagnosed with invasive BC using a large population-based cohort of Dutch BC
patients, taking age, mode of first BC detection, and (neo)adjuvant systemic
therapy into account. In addition, the authors evaluated the CBC risk prediction
performance in patients diagnosed with DCIS.

Women diagnosed with DCIS (N=28,003) or stage I-III BC
(N=275,836) between 1989-2017 were identified from the nationwide Netherlands
Cancer Registry. Cumulative incidences were estimated, accounting for competing
risks, and hazard ratios (HRs) for metachronous invasive CBC. To evaluate effects
of adjuvant systemic therapy and screening, separate analyses were performed
for stage I BC without adjuvant systemic therapy and by mode of first BC
detection. Multivariable models including clinico-pathological and treatment
data were created to assess CBC risk prediction performance in DCIS patients.

For more details on the methodology, please read the related
article.

Data supporting the figures, tables, and supplementary files in the
article: Dataset NKR_K18.245.txt, is in text file
format, and supports the findings of this study. This file will be made available upon reasonable request, as described in the data access section above. The following datasets are in
Excel file format, support figures 1 and 2, and supplementary figures 2-4,
respectively, and are part of this figshare data record: Underlying data_Figure 1.xlsx, Underlying
data_Figure 2.xlsx, Underlying
data_Supplementary Figure 1.xlsx, Underlying
data_Supplementary Figure 2.xlsx and Underlying
data_Supplementary Figure 3.xlsx. The aforementioned Excel files show the
underlying data points of the cumulative incidence figures provided in the article.

本研究旨在对比导管原位癌（ductal carcinoma in situ, DCIS）患者与浸润性乳腺癌（invasive breast cancer, BC）患者的对侧乳腺癌（contralateral breast cancer, CBC）发病风险。

数据获取：本研究生成和/或分析的数据集暂未公开，因本研究使用了荷兰癌症登记处（Netherlands Cancer Registry）的外部数据。合理申请后可从荷兰癌症登记处获取本研究数据集（数据申请编号：K18.245）。如需申请数据访问，请访问：https://www.iknl.nl/en/ncr/apply-for-data。支持本文图1、图2及补充图2-4的数据集已作为本数据记录的一部分，公开上传至figshare知识库。

研究伦理审批：荷兰癌症登记处隐私审查委员会（NCR Privacy Review Board）批准了本研究方案。所有数据均按照医学研究隐私法规进行处理。

研究目标与方法：对侧乳腺癌（CBC）是首诊浸润性乳腺癌（BC）后最常见的继发恶性肿瘤。女性罹患浸润性乳腺癌后，侵袭性对侧乳腺癌的年累积发病率约为0.4%。多项研究表明，（新）辅助全身治疗可降低CBC的发病风险。本研究旨在利用荷兰大型基于人群的乳腺癌患者队列，在匹配年龄、首诊乳腺癌检出方式及（新）辅助全身治疗因素的前提下，直接对比DCIS患者与确诊浸润性乳腺癌患者的侵袭性对侧乳腺癌发病风险。此外，本研究还评估了DCIS患者的CBC发病风险预测性能。

本研究从荷兰全国癌症登记处筛选出1989年至2017年间确诊的DCIS患者（N=28003）及I-III期BC患者（N=275836）。研究采用竞争风险模型估算累积发病率，并计算异时性侵袭性CBC的风险比（hazard ratio, HR）。为评估辅助全身治疗与筛查的影响，本研究针对未接受辅助全身治疗的I期BC患者，并按首诊BC检出方式分别开展了亚组分析。此外，本研究构建了包含临床病理及治疗数据的多变量模型，以评估DCIS患者的CBC发病风险预测性能。

如需了解研究方法的更多细节，请参阅相关研究论文。

本文图表、表格及补充文件的支撑数据如下：数据集NKR_K18.245.txt为文本格式，用于支撑本研究的研究结论，可按前文数据获取章节所述的合理申请流程获取。以下为Excel格式的数据集，分别对应图1、图2及补充图2-4，已作为本figshare数据记录的一部分公开：Underlying data_Figure 1.xlsx、Underlying data_Figure 2.xlsx、Underlying data_Supplementary Figure 1.xlsx、Underlying data_Supplementary Figure 2.xlsx及Underlying data_Supplementary Figure 3.xlsx。上述Excel文件包含了本文中累积发病率图表的原始数据点。