Role of contrast-enhanced spectral mammography in the assessment of residual disease following neoadjuvant chemotherapy in patients with breast cancer

Background: Neoadjuvant chemotherapy (NAC) is currently one of the most commonly utilized treatment options for patients with breast cancer. Evaluating residual disease following NAC is vital in post-chemotherapy treatment planning. Underestimation or overestimation of the residual disease may result in incomplete surgical resection or unnecessary aggressive surgical treatment which can compromise patient survival or result in unwanted morbidity. Contrast-enhanced spectral mammography (CESM) is a new imaging modality that can provide both morphological and anatomical characterization of neoplastic breast lesions when MRI is unavailable or contraindicated. The aim of this prospective observational study was to evaluate the value of CESM in assessing the extent of residual disease following NAC and predicting complete response (CR) with histopathology as the gold standard. Results: A total of 142 patients were included in our study with invasive duct carcinoma the most prevalent histopathological type seen in 81.7% of cases. The average tumor reduction in size was 40.8% by CESM and 35.8% by histopathology. Comparison between maximum tumor diameter after NAC by CESM and histopathology revealed a high degree of correlation (R = 0.918, p < 0.01). In 45.1% of cases, CESM underestimated the residual tumor size by an average of 1.1 cm. Comparison between CESM and histopathology in predicting CR yielded CESM sensitivity, specificity, positive predictive value (PPV), and negative predictive values (NPV) of 96.7%, 84.6%, 97.2%, and 100%, respectively. Conclusions: CESM is a new effective imaging modality in assessing residual disease in breast cancer patients receiving NAC. Post-NAC CESM correlated well with residual tumor size by histopathology with a tendency for underestimation. Careful assessment of CESM images should be made to accurately measure the exact tumor size to avoid overestimation or underestimation potentially increasing the extent of the operation. Proper assessment of the true extent of residual disease can help the surgeon to select the optimal surgical technique ensuring radical treatment of the disease improving patient survival and reducing morbidity.