Imaging Features of Breast Cancer Subtypes on Mammography and Ultrasonography: an Analysis of 479 Patients

To compare features of clinically defined subtypes of breast cancer on mammography (MG) and ultrasonography (USG). After obtaining approval from the institute ethics committee, a retrospective observational study was performed on biopsy-proven breast cancer patients who underwent baseline MG from 2016 to 2020. MG and USG features were evaluated and the patients were classified based on immunohistochemistry profile into luminal like (LL)-oestrogen receptor (ER)/progesterone receptor (PR) + , Her2neu-; basal like (BL)-ER/PR-, Her2neu-; Her2 like (HL)-Her2neu + . A total of 479 patients (mean age, 51.4 +/- 11.7 years; all females) were included: LL-198 (41.3%), BL-121 (25.2%) and HL-160 (33.3%). On MG, round shape (21/115, 18.3%, p < 0.001); circumscribed (16/115, 13.9%, p < 0.001) and microlobulated margins (28/115, 24.4%) were associated with BL tumours. Associated suspicious calcifications (96/160, 60%, p < 0.001) and skin thickening or retraction (75/149, 50.3%, p < 0.001) were more common in HL. On USG, round shape (12/95, 12.8%, p = 0.005); circumscribed (8/94, 8.5%) and microlobulated margins (44/94, 46.8%) and posterior acoustic enhancement (7/95, 7.5%, p = 0.012) were associated with BL. The logistic regression analysis revealed that spiculated margins on MG favoured LL (OR: 8.5, p = 0.001); round shape (OR: 6.8), circumscribed (OR: 10.8) or microlobulated margins (OR: 3.5) (p < 0.001 for each) favoured BL; whereas associated features of calcifications (OR: 3.3) (p = 0.019) and skin retraction or thickening (OR: 1.8) (p < 0.001) favoured HL. On USG, circumscribed (OR: 5.9, p = 0.005) or microlobulated margins (OR: 3, p < 0.001) and posterior acoustic enhancement (OR: 9.5, p = 0.006) favoured BL. Clinically defined subtypes of breast cancer show significant differences in the imaging appearances on mammography and USG. BL tumours may not show the typical imaging features of malignancy, necessitating clinicopathological correlation for accurate diagnosis.