Purpose: To prospectively compare the ability of clinical examination, mammography, vascularity-sensitive ultrasound, and magnetic resonance imaging (MRI) to determine pathologic complete response (CR) in breast cancer patients undergoing neoadjuvant chemotherapy.
Patients and methods: Participants were women with primary measurable, operable invasive breast cancer (Stages I-III) who presented to the University of Michigan Breast Care Center. Eligibility criteria were based on clinical need for chemotherapy as part of the overall treatment plan. The chemotherapy consisted of doxorubicin and docetaxel administered every 3 weeks for four cycles. Tumor size measurements by physical examination and by the three imaging modalities were performed before chemotherapy was initiated and after its completion, prior to definitive surgery. Response criteria were pre-specified in this prospective design, and study radiologists analyzed the mammographic, sonographic and MRI image sets blinded to information from the other modalities and blinded to final histological diagnosis. The pathologic CR rate obtained by the clinical and imaging modalities was compared to pathologic CR as determined pathologically.
Results: 41 of 43 enrolled patients had a determination of pathologic response, and 4 patients had a pathologic CR to this chemotherapy (9.8%). The accuracy of physical examination, mammography, ultrasound, and MRI in determining pathologic CR was 75, 89, 82, and 89% respectively (NS).
Conclusion: Biopsy after neoadjuvant chemotherapy remains absolutely necessary to determine pathologic CR to neoadjuvant chemotherapy, as the accuracy of current imaging modalities is insufficient to make this determination. The accuracy of mammography, vascularity-sensitive ultrasound, and MRI were not observed to be significantly different.