Breast cancer subtype influences the accuracy of predicting pathologic response by imaging and clinical breast exam after neoadjuvant chemotherapy

Abstract

Background/Aim: Clinical response evaluation after neoadjuvant chemotherapy (NACT) for breast cancer could include various imaging methods, as well as clinical breast exam (CBE). We assessed the accuracy of CBE and imaging to predict pathologic response after NACT administration according to breast cancer subtype. Patients and Methods: This retrospective cohort study included 84 patients with records of NACT and subsequent primary breast surgery from 2003-2013. Patients were divided into 4 breast cancer subtypes according to hormone receptor (HR) status and human epidermal growth factor receptor-2 (HER2) status. Negative predictive value (NPV), false-negative rate (FNR), false-positive rate (FPR) and positive predictive value (PPV) were calculated for CBE and imaging post-NACT and prior to breast cancer surgery. Results: NPV, FNR, FPR and PPV varied by breast cancer subtype and clinical response evaluation method. Imaging resulted in a higher NPV and a lower FNR than CBE among the entire cohort. There was a lower FPR with CBE. Clinical response evaluation by CBE was highly accurate for predicting pathologic residual disease in HR+ tumors (CBE PPV: 95.5% in HR+HER2-, 100.0% in HR+HER2+). In triple-negative breast cancer (TNBC), the imaging NPV was 100% and the imaging FNR was 0%. Conclusion: The use of imaging in HR+ tumors post-NACT may provide little to no additional value that is not already garnered by performance of a CBE. For TNBC, imaging may play a critical role in the prediction of pathologic complete response (PCR) post-NACT.