Neoadjuvant chemotherapy (NAC) results in a pathologic complete response (pCR), which has been shown to be associated with disease-free survival and overall survival. The apparent diffusion coefficient (ADC) indicates the stability of water molecules, and the ADC has been used to predict the response of solid tumors to chemotherapy. We therefore evaluated the ability of dynamic contrast-enhanced MRI (DCE-MRI) and diffusion-weighted imaging (DWI) to help predict pCR in patients with breast cancer treated with NAC.
From August 2013 to July 2016, 39 patients (mean age, 53 years; age range, 31–72 years) were treated with the nanoparticle albumin-bound paclitaxel (nab-PTX) (260 mg/m2; q3w for 4 cycles) ± concurrent trastuzumab (8mg, 6mg/Kg; q3w for 4 cycles) followed by the FEC100 (5-fluorouracil/epirubicin/cyclophosphamide, 500/100/500 mg/m2; q3w for 4 cycles). pCR was defined as the absence of any residual invasive cancer or ductal carcinoma in situ. Radiologic complete response (rCR) was defined as the absence of tumor enhancement. The ADC ratio (post FEC ADC/pre nab-PTX ADC) was calculated.
Tumor phenotypes were found to be triple negative (TN) (n = 20) and human epidermal growth factor receptor 2 (HER2) positive (n = 19). pCR was achieved in 21 patients [54%]. rCR was observed in 17 patients [44%] . The mean pre nab-PTX ADC and ADC ratios were not associated with pCR in either phenotype (p = 0.57, p = 0.379 for TN disease; and p = 0.238, p = 0.168 for HER2-positive disease). By using receiver operating characteristic (ROC) analysis with the ADC ratio, the area under the curve (AUC) was 0.525 [95% confidence interval (CI): 0.24–0.811] in TN disease and 0.722 [95% CI: 0.449–0.995] in HER2-positive disease. According to radiologic responses and pathological responses, the ADC ratio in rCR plus pCR in TN disease was not changed among other response groups (ADC: 3.68±2.91), whereas it was higher than that in the other response groups in HER2-positive disease (ADC: 5.95±4.07).
A high ADC ratio in DWI plus rCR in DCE-MRI may be promising findings for the successful prediction of response in patients with HER2-positive breast cancer rather than in patients with TN breast cancer treated with NAC.
Clinical trial identification
Legal entity responsible for the study
Yokkaichi Municipal Hospital
All authors have declared no conflicts of interest.