School of Medicine, University of California, San Francisco, San Francisco, CA, USA.
Department of Surgery, University of California, 1825 4th Street, 3rd Floor, Box 1710, San Francisco, CA, 94143, USA.
Breast Cancer Res Treat. 2023 Nov;202(2):367-375. doi: 10.1007/s10549-023-07059-y. Epub 2023 Jul 27.
Recent guidelines defined a new reporting category of ER-low-positive breast cancer based on immunohistochemistry (IHC). While low positivity of either hormone receptor is uncommon in invasive lobular carcinoma (ILC), we sought to investigate whether relatively low hormone receptor positivity was associated with tumor characteristics and patient outcomes in a single institutional cohort.
We searched an institutional database for cases of stage I-III ILC with available IHC reports. Based on prior published categories in ILC, ER was classified as low, medium, or high as defined by ER staining of 10-69%, 70-89%, and ≥ 90% respectively. PR low and high tumors were defined by < 20%, or ≥ 20% staining respectively. We used chi-squared tests, t-tests, and Cox proportional hazards models to evaluate associations between ER/PR categories and tumor characteristics or disease-free survival (DFS).
The cohort consisted of 707 ILC cases, with 11% of cases categorized as ER low, 15.1% as medium, and 73.8% as high. The majority (67.6%) were PR high. Patients with ER low/medium expression were significantly younger, and more likely to also have PR low and/or HER2 positive tumors compared to those that were ER high. In a Cox proportional hazards model adjusting for age, stage, grade, pleomorphic histology, and treatment, ER category was not prognostic for DFS, but PR negative and PR low status each had significantly worse DFS compared to PR high status (HR 3.5, 95% CI 1.8-6.7, p < 0.001; and HR 2.0, 95% CI 1.1-3.5, p = 0.015, respectively).
These findings highlight the relevance of quantifying ER and PR within ILC.
最近的指南根据免疫组织化学（IHC）定义了一种新的 ER 低阳性乳腺癌报告类别。虽然低激素受体阳性在浸润性小叶癌（ILC）中并不常见，但我们试图在单个机构队列中研究相对较低的激素受体阳性是否与肿瘤特征和患者结局相关。
我们在机构数据库中搜索了具有可用 IHC 报告的 I 期-III 期 ILC 病例。根据 ILC 中先前发表的类别，ER 被分为低、中或高，分别定义为 ER 染色为 10-69%、70-89%和≥90%。PR 低和高肿瘤分别定义为染色<20%或≥20%。我们使用卡方检验、t 检验和 Cox 比例风险模型来评估 ER/PR 类别与肿瘤特征或无病生存期（DFS）之间的关联。
该队列包括 707 例 ILC 病例，其中 11%的病例被归类为 ER 低，15.1%为中，73.8%为高。大多数（67.6%）为 PR 高。与 ER 高的患者相比，ER 低/中表达的患者年龄明显更小，并且更有可能同时存在 PR 低和/或 HER2 阳性肿瘤。在调整年龄、分期、分级、多形性组织学和治疗的 Cox 比例风险模型中，ER 类别与 DFS 无关，但 PR 阴性和 PR 低状态与 PR 高状态相比，DFS 显著更差（HR 3.5，95%CI 1.8-6.7，p<0.001；和 HR 2.0，95%CI 1.1-3.5，p=0.015，分别）。
这些发现强调了在 ILC 中定量 ER 和 PR 的相关性。
