ABSTRACT
INTRODUCTION: The present study aims to determine the diagnostic accuracy of magnetic resonance imaging (MRI) and positron emission tomography-computed tomography (PET-CT) in predicting a pathological response of molecular subtypes of breast cancer to neoadjuvant chemotherapy (NAC). MATERIALS AND METHODS: We retrospectively analyzed patients with breast cancer who were operated after NAC between January 2018 and May 2020. Radiological responses were evaluated as per the Response Evaluation Criteria in Solid Tumors (RECIST) and changes in contrast enhancement patterns on MRI and the classification of PET Response Criteria in Solid Tumors (PERCIST) on PET-CT. The presence of a pathological response was evaluated based on the Sataloff classification. The agreement between the radiological response determined through imaging modalities before and after the NAC and the postoperative pathological complete response (pCR) was evaluated and compared statistically. Among the patients diagnosed with breast cancer between the ages of 18 and 80 y, those with N (+) at the time of diagnosis, those with T2 and advanced tumors, and those who were planned for breast conserving surgery were included in our study. Male patients, patients with distant metastases at the time of diagnosis, and patients with other system malignancies were excluded. RESULTS: The study included 88 patients who had undergone surgery for breast cancer after NAC between January 2018 and May 2020. The study was conducted retrospectively in a single center. The tumor diameters and standard uptake values significantly decreased after NAC (P < 0.001). Estrogen receptor (ER) and progesterone receptor (PR) positivity were negatively associated with pCR (P = 0.03 and P = 0.03, respectively), whereas there was a significant positive association between HER-2 positivity and pCR (P = 0.004). There was a moderate agreement between the RECIST criteria used with MRI and pCR (k: 0.46). Moreover, a good agreement between PET-CT-PERCIST and pCR was detected (k: 0.61). In predicting pCR after NAC, MRI showed a selectivity of 80.7%, a sensitivity of 65.2%, a positive predictive value (PPV) of 75%, and a negative predictive value (NPV) of 72.4%. The corresponding rates for PET-CT were 75.7%, 100%, 57.9%, and 100%. CONCLUSIONS: When evaluating pCR after NAC, MRI was found to be more sensitive in patients with ER-positive cancer cell nuclei with weak to medium staining intensity and a loss of E-cadherin expression, whereas PET-CT was found to be more sensitive in patients with HER-2 overexpression, Luminal B, or Ki-67 proliferation >14% (P = 0.01).
