Ultrasonography: an aid in molecular subtyping of breast carcinoma

The recognition of molecular subtypes of breast cancer has initiated a new regimen of targeted therapy. Early diagnosis is a key step in improving survival. Therefore, a cost-effective and widely available imaging tool is needed for the timely detection and prediction of the molecular profile of breast cancer.

To study the predictive value of ultrasonographic features in identifying the estrogen receptor, progesterone receptor, human epidermal growth factor receptor 2 neu (HER2/neu) expression status, and molecular subtypes of breast cancer.

We conducted a study on 51 histopathologically proven invasive breast carcinoma cases over a period of one and a half years. The patients underwent ultrasonography followed by tissue biopsy. Sonographic parameters were assessed based on BI-RADS imaging features. The molecular subtypes of breast cancer were grouped into four subtypes based on the St. Gallen International Expert Consensus Panel. The predictive value of ultrasonographic features was then studied in relation to the hormone receptor status and molecular subtypes of breast cancer.

A significant association between posterior acoustic features and molecular subtypes was seen. Posterior acoustic shadowing was associated with progesterone receptor status with an odds ratio (OR) of 36.58, confidence interval (CI) of 5.527-866.1, and p <0.001. The luminal type A molecular subtype was significantly higher in the posterior acoustic shadowing group (10 cases; 52.63%) with an OR of 3.85, CI of 1.12-13.98, and p of 0.02. The proportion of patients with triple-negative molecular subtype (9 cases, 50%) was significantly higher in the posterior acoustic enhancement group, with an OR of 29.42, CI of 4.117-725.4, and p <0.001. Tumors with circumscribed margins were also highly suggestive of the triple-negative molecular subtype [OR of 5.12, CI of 1.16-24.85, and p of 0.03]. The association between the presence or absence of vascularity and its type with molecular subtypes failed to show statistical significance in our study, although vascularity was more frequently observed in triple-negative molecular subtype and luminal type B Her+ve cases.

Certain sonographic features are associated with the estrogen/progesterone receptor hormone receptor status and molecular subtypes of breast cancer. With validation of this association, ultrasound may serve as a basic imaging modality for predicting molecular subtypes of breast cancer even in remote areas, where immunohistochemistry hormone receptor and HER2 testing are not available.