The impact of HER2 status in ductal carcinoma in situ (DCIS) on the risk of progression to invasive ductal carcinoma (IDC) has been debated. We aim to use a national database to identify patients with known HER2 status to elucidate the effect of HER2 overexpression on ipsilateral IDC (iIDC) development. We performed survival analysis on patient-level data using the U.S. NCI's Surveillance Epidemiology and End Results program. We identified patients diagnosed with DCIS who underwent lumpectomy and had known HER2 status. Competing risks analysis was performed. A total of 1,540 patients had known HER2 status and met inclusion criteria. Median age at diagnosis was 60, median follow-up time was 44.5 months. A total of 417 (27.1%) patients were HER2 positive and 1,035 (67.2%) were HER2 negative. Twenty-two (1.4%) patients developed iIDC and 27 (1.8%) developed ipsilateral in situ or contralateral disease. The estimated cumulative incidence of iIDC at 5 years was 1.9% for all patients, 1.2% for HER2-negative and borderline patients, and 3.9% for HER2-positive patients. On multivariate competing risks regression, two factors were significant for iIDC: radiation (protective) therapy within 24 months (HR, 0.05; P = 0.00006) and HER2 overexpression (increased likelihood; HR, 2.72; P = 0.044). Patients with HER2-positive DCIS were more likely to have recurrences with receptor discordance. HER2 may serve as a prognostic factor for invasive recurrence and was the only lesion-related factor to significantly relate to iIDC development. It may also be associated with receptor discordance of recurrences. Further large studies will be needed to confirm these results.

中文翻译：

---

HER2 过度表达的导管原位癌与同侧侵袭性复发风险增加相关，受体与复发不一致

HER2 状态在导管原位癌 (DCIS) 中对进展为浸润性导管癌 (IDC) 风险的影响一直存在争议。我们的目标是使用国家数据库来识别具有已知 HER2 状态的患者，以阐明 HER2 过表达对同侧 IDC (iIDC) 发展的影响。我们使用美国 NCI 的监测流行病学和最终结果程序对患者级别的数据进行了生存分析。我们确定了接受乳房肿瘤切除术且已知 HER2 状态的诊断为 DCIS 的患者。进行了竞争风险分析。共有 1,540 名患者已知 HER2 状态并符合纳入标准。诊断时的中位年龄为 60 岁，中位随访时间为 44.5 个月。共有 417 名 (27.1%) 患者为 HER2 阳性，1,035 名 (67.2%) 为 HER2 阴性。22 名 (1.4%) 患者出现 iIDC，27 名 (1. 8%) 发生同侧原位或对侧疾病。所有患者 5 年 iIDC 的估计累积发生率为 1.9%，HER2 阴性和临界患者为 1.2%，HER2 阳性患者为 3.9%。在多变量竞争风险回归中，iIDC 有两个重要因素：24 个月内的放射（保护性）治疗（HR，0.05；P = 0.00006）和 HER2 过度表达（可能性增加；HR，2.72；P = 0.044）。HER2 阳性 DCIS 患者更有可能因受体不一致而复发。HER2 可作为侵袭性复发的预后因素，并且是唯一与 iIDC 发展显着相关的病变相关因素。它也可能与复发的受体不一致有关。需要进一步的大型研究来证实这些结果。