Objectives: To perform the first national analysis of demographic and clinicopathological features associated with the HER2 positive, HER2-low, and HER2-zero invasive breast cancers in New Zealand. The study will reveal the proportion of women who may benefit from new HER2-targeted antibody drug conjugate (ADC) therapies. Methods: Utilising data from Te Rēhita Mate Ūtaetae (Breast Cancer Foundation NZ National Register), the study analysed data from women diagnosed with invasive breast cancer over a 21-year period. The HER2 status of tumours was classified into three categories—HER2-zero, HER2-low, HER2-positive. Results: From 2009–2021, 94% of women underwent HER2 testing, with 14% diagnosed with HER2-positive breast cancer. For advanced-stage disease, 38% of those formerly classified as HER2-negative were reclassified as HER2-low. Including HER2-positive breast cancers, this indicates that 60% of women with advanced breast cancer may potentially benefit from the new HER2-directed ADCs (approximately 120 women per year). Conclusions: The findings suggest a significant proportion of women with invasive breast cancer in New Zealand could benefit from new HER2-targeted treatments. There is a need to standardise HER2 testing to enhance personalised treatment and improve outcomes.
目的：对新西兰HER2阳性、HER2低表达及HER2零表达型浸润性乳腺癌的人口统计学与临床病理学特征进行首次全国性分析。本研究将揭示可能受益于新型HER2靶向抗体偶联药物治疗的女性患者比例。方法：研究利用新西兰乳腺癌基金会国家登记库数据，对21年间确诊的浸润性乳腺癌女性患者资料进行分析。根据肿瘤HER2状态分为三类：HER2零表达、HER2低表达及HER2阳性。结果：2009至2021年间，94%的女性患者接受了HER2检测，其中14%确诊为HER2阳性乳腺癌。在晚期乳腺癌患者中，原分类为HER2阴性的病例有38%被重新归类为HER2低表达。结合HER2阳性病例，这意味着60%的晚期乳腺癌女性可能受益于新型HER2靶向抗体偶联药物治疗（每年约120例）。结论：研究结果表明新西兰相当比例的浸润性乳腺癌女性患者可能受益于新型HER2靶向治疗。有必要建立标准化的HER2检测体系以推进个体化治疗并改善临床预后。
Analysis of HER2-Low Breast Cancer in Aotearoa New Zealand: A Nationwide Retrospective Cohort Study
肿瘤(癌症)患者之家