新辅助系统治疗（NST）可使乳腺癌患者的病理学完全缓解率（pCR）达10-89％，取决于亚型。在达到pCR的患者中，手术的附加价值尚不确定；但是，目前用于预测pCR的影像和活检技术精度不够。本研究旨在量化在MRI响应良好且活检遗漏残留病变的患者中，NST后遗留的残留病变。在MICRA试验中，对于MRI上对NST响应良好的患者，进行超声指导的NST后14G活检和手术。我们分析了活检和手术标本的病理学报告。主要结果是在分子亚型中残留浸润性疾病的程度，次要结果是遗漏残留浸润性疾病的程度。我们包括167名患者。手术标本显示69名（41％）患者有残留浸润性疾病。激素受体阳性（HR +）/人类表皮生长因子受体2阴性（HER2-）患者的残留浸润性疾病中位数大小为18毫米（四分位距[IQR] 12-30），HR + / HER2 +患者为8毫米（IQR 3-15），HR阴性（HR-）/ HER2 +患者为4毫米（IQR 2-9），而三阴性（TN）患者为5 mm（IQR 2-11）。在所有亚型中，遗漏的残留浸润性疾病从4到7毫米不等。尽管TN和HER2 +亚型的残留浸润性疾病范围很小，但是所有亚型都留下了大量的残留浸润性疾病使用14G活检。这可能阻碍局部控制，并限制辅助系统治疗选择。因此，手术切除仍然是必需的，直到影像和活检技术的准确性得到改善。©2023年。作者（们）。

Neoadjuvant systemic treatment (NST) leads to pathologic complete response (pCR) in 10-89% of breast cancer patients depending on subtype. The added value of surgery is uncertain in patients who reach pCR; however, current imaging and biopsy techniques aiming to predict pCR are not accurate enough. This study aims to quantify the residual disease remaining after NST in patients with a favorable response on MRI and residual disease missed with biopsies.In the MICRA trial, patients with a favorable response to NST on MRI underwent ultrasound-guided post-NST 14G biopsies followed by surgery. We analyzed pathology reports of the biopsies and the surgical specimens. Primary outcome was the extent of residual invasive disease among molecular subtypes, and secondary outcome was the extent of missed residual invasive disease.We included 167 patients. Surgical specimen showed residual invasive disease in 69 (41%) patients. The median size of residual invasive disease was 18 mm (interquartile range [IQR] 12-30) in hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) patients, 8 mm (IQR 3-15) in HR+/HER2-positive (HER2+) patients, 4 mm (IQR 2-9) in HR-negative (HR-)/HER2+ patients, and 5 mm (IQR 2-11) in triple-negative (TN) patients. Residual invasive disease was missed in all subtypes varying from 4 to 7 mm.Although the extent of residual invasive disease is small in TN and HER2+ subtypes, substantial residual invasive disease is left behind in all subtypes with 14G biopsies. This may hamper local control and limits adjuvant systemic treatment options. Therefore, surgical excision remains obligatory until accuracy of imaging and biopsy techniques improve.© 2023. The Author(s).