Abstract PO3-07-09: B3 breast lesions in Asian Centers: malignant upgrade rates and risk factors
Authors: Ang Wei Wen , Jung Ji-Jung 
Published: May 2024

Background Lesions of uncertain malignant potential in the breast (B3 lesions) are composed of a wide spectrum of pathologies with differing risks of breast cancer. With the widespread implementation of screening programs globally, the incidence of these lesions has increased substantially. Asian women tend to have smaller and denser breasts than Western women, making identifying and treating these lesions more challenging. Previous papers quote an upgrade of B3 lesions to malignancy such as ductal carcinoma in situ (DCIS) or cancer at rates of 9.9% to 35.1%. Malignant upgrade on final histology increases patient anxiety and healthcare costs as a second surgical intervention is often required for pathological clearance or lymph node staging. This study aimed to assess the malignant upgrade rate of B3 lesions in Asian women and to evaluate any key factors that may predict the risk of a malignant upgrade. Materials and Methods A retrospective multicentre international study was done on patients at Seoul National University Hospital (SNUH), South Korea, from April 2021 to 2023, and Tan Tock Seng Hospital (TTSH), Singapore, between March 2006 and 2023. Patients who were diagnosed with a B3 lesion on initial breast core needle biopsy and underwent surgical open excision were included in the study. Results A total of 1049 patients were diagnosed with B3 lesions, with 154 (14.7%) upgrading to malignancy. The most common malignancy was DCIS, 118 (76.6%), followed by invasive ductal carcinoma (IDC), 20 (13.0%) and papillary carcinoma, 4 (2.6%). Within the types of B3 lesions, the malignant upgrade rates were found: atypical ductal hyperplasia (ADH), 88/252 (35%); intraductal papilloma (IDP) with atypia, 16/55 (29%); lobular neoplasia (LN), 9/34 (26%); and radial scar (RS), 5/21 (24%). Most patients had both ultrasound and mammographic evaluation, and all lesions in the study were graded BIRADS 4A and above. Univariate analysis showed that age &gt;50 (OR 2.30 [1.61-3.31], p&lt; 0.001), BMI &gt;23 (OR 2.21 [1.20-4.12], p=0.01), post-menopausal status (OR 2.43 [1.34-4.34], p&lt; 0.001), lesion being identified on mammography (OR 3.00 [2.04-4.51], p&lt; 0.001) and presence of microcalcifications on mammography (OR 0.63 [0.41-0.98], p=0.04) were risk factors for malignant upgrade. Conclusion Based on our analysis of Asian women, post-menopausal patients with microcalcifications on mammography and a B3 biopsy result should be treated with a higher degree of suspicion for underlying malignancy. Surgical excision with adequate margins should be routinely considered for B3 lesions such as ADH, IDP with atypia, LN and RS. Avoidance of surgery or vacuum-assisted removal can be considered for younger patients with only ultrasound findings and diagnosis of FEA and IDP.

Table 1. Malignant upgrade after excision

Table 2. Clinical characteristics of all patients according to malignant upgrade

Table 3. Univariate and multivariate analysis for malignant upgrade

Citation Format: Wei Wen Ang, Ji-Jung Jung. B3 breast lesions in Asian Centers: malignant upgrade rates and risk factors [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO3-07-09.