Supplementary Material for: Malignancy Rate and Malignancy Risk Assessment in Different Lesions of Uncertain Malignant Potential in the Breast (B3 Lesions): An Analysis of 192 Cases from a Single Institution

<b><i>Background:</i></b> The question of how to deal with B3 lesions is of emerging interest. <b><i>Methods:</i></b> In the breast diagnostics of 192 patients between 2009 and 2016, a minimally invasive biopsy revealed a B3 lesion with subsequent resection. This study investigates the malignancy rate of different B3 subgroups and the risk factors that play a role in obtaining a malignant finding. <b><i>Results:</i></b> The distribution of B3 lesions after minimally invasive biopsy was as follows: atypical ductal hyperplasia (ADH), 7.3%; flat epithelial atypia (FEA), 7.8%; lobular neoplasia (LN), 7.8%; papilloma (Pa), 49.5%; phylloidal tumour (PT), 8.9%; radial sclerosing scar (RS), 3.1%; mixed findings, 10.4%; and other B3 lesions, 5.2%. Most B3 lesions were detected by stereotactic vacuum-assisted biopsy (44.3%), 36.5% by ultrasound-assisted biopsy, and 19.3% by magnetic resonance imaging-assisted biopsy. Most B3 lesions (55.2%) were verified by surgical resection, whereas 30.7% were downgraded to a benign lesion. About 14.1% of the cases were upgraded to malignant lesions, 9.4% to ductal carcinoma in situ and 4.7% to invasive carcinoma. In relation to individual B3 lesions, the following malignancy rates were found: 28.6% (ADH), 13.3% (FEA), 33.3% (LN), 12.6% (Pa), 5.9% (PT), and 0% (RS). The most important risk factor was increasing age. Postmenopausal status was considered an increased risk for an upgrade (<i>p =</i> 0.015). A known malignancy in the ipsilateral breast was a significant risk factor for a malignant upgrade (<i>p =</i> 0.003). <b><i>Conclusion:</i></b> Increasing knowledge about B3 lesions allows us to develop a “lesion-specific” therapy approach in the heterogeneous group of B3 lesions, with follow-up imaging for some lesions with less malignant potential and concordance with imaging or further surgical resection in cases of disconcordance with imaging or higher malignant potential.

**背景**：如何处理B3病变（B3 lesions）已渐成临床研究热点。
**方法**：本研究纳入2009年至2016年间接受乳腺诊疗的192例患者，所有受试者经微创活检确诊为B3病变，且后续均接受手术切除。本研究旨在分析不同B3病变亚组的恶性转化率，以及与恶性病理结局相关的危险因素。
**结果**：微创活检检出的B3病变分布如下：非典型导管增生（atypical ductal hyperplasia, ADH）占7.3%；扁平上皮非典型增生（flat epithelial atypia, FEA）占7.8%；小叶肿瘤变（lobular neoplasia, LN）占7.8%；乳头状瘤（papilloma, Pa）占49.5%；叶状肿瘤（phylloidal tumour, PT）占8.9%；放射状硬化性瘢痕（radial sclerosing scar, RS）占3.1%；混合性病变占10.4%；其他B3病变占5.2%。
B3病变的检出方式分布为：立体定向真空辅助活检占44.3%，超声辅助活检占36.5%，磁共振成像辅助活检占19.3%。
手术切除病理证实，55.2%的B3病变与术前活检结果一致；30.7%的病变病理级别降级为良性病变；约14.1%的病例病理级别升级为恶性病变，其中9.4%为导管原位癌，4.7%为浸润性癌。
针对不同亚型的B3病变，其恶性转化率分别为：非典型导管增生（ADH）28.6%、扁平上皮非典型增生（FEA）13.3%、小叶肿瘤变（LN）33.3%、乳头状瘤（Pa）12.6%、叶状肿瘤（PT）5.9%、放射状硬化性瘢痕（RS）0%。
本研究发现，年龄增长是最主要的危险因素。绝经后状态为病变升级的高危因素（p=0.015）；同侧乳腺既往存在恶性肿瘤病史，则是病变升级为恶性的显著危险因素（p=0.003）。
**结论**：随着对B3病变认识的不断深入，我们可为异质性的B3病变群体制定"病变特异性"诊疗方案：对于恶性潜能较低的病变，可采取影像学随访；对于与影像学结果不符或恶性潜能较高的病变，则需行影像学一致性评估，或进一步实施手术切除。