Imaging of HER2 detected receptor expression positive breast cancer: from detection to interpretation

Abstract

Abstract Background Aggressive invasion, high recurrence rate, and poor prognosis are common features of the human epidermal growth factor receptor-2 (HER2)-enriched breast cancer, yet on the other side, it shows significantly reduced activity in response to therapy. We aimed to find combinations of features at imaging modalities that could predict breast cancer HER2-enriched molecular subtype in a sample of screening and symptomatic patients. Methods The study is a retrospective analysis including breast lesions proved to be cancer with HER2 detected receptor expression positive (n = 346) whether pure or expressed with other receptors (i.e., luminal B subtype). All carcinomas were examined by digital mammography and high-resolution breast ultrasound. Some cases (n = 148, 48.5%) were considered for further evaluation by contrast enhanced mammography or dynamic post-contrast MR imaging (n = 116, 33.5%) in case there was a diagnosis debate and/or a precise estimation of cancer multiplicity is needed. Results Six features were suggestive of HER-enriched carcinoma on mammogram and/or ultrasound; (1) irregular shape mass, (2) indistinct margin, (3) associate fine pleomorphic microcalcifications, (4) asymmetry of global distribution, (5) hypoechoic pattern on ultrasound and (6) enlarged pathological nodes. There was a significant correlation between HER2-enriched subtype and presence of fine pleomorphic calcifications (p = < 0.02) of segmental distribution (p = < 0.002) and asymmetry of global distribution (p = < 0.001). Contrast-based studies' dominant feature was the non-mass appearance of regional/diffuse distribution. Medium initial contrast uptake and wash out fate were the common curve pattern (p = < 0.001). Conclusions Luminal B and HER2 enriched are both HER 2 overexpression breast cancer subtypes, yet there are certain key features more specific for HER2 enriched subtype in conventional and contrast-based imaging. Knowledge of such features could help interpretation and differentiation between HER2 positive subtypes to benefit from the early stratification of management and aid the therapeutic decisions in case receptor testing is not readily available.