The probability of axillary pathologic complete response in patients with breast radiologic complete response on breast MRI in triple-negative breast cancer treated with neoadjuvant chemotherapy

Introduction Accurately identifying patients with axillary pathologic complete response (pCR) following neoadjuvant chemotherapy (NACT) remains challenging.The probability of axillary pCR is correlated with experiencing breast pCR, particularly in triple-negative breast cancer (TNBC).This study aimed to determine the probability of ypN0 in the occasion of breast radiologic complete response (rCR) on breast MRI, and compare the diagnostic performance of mid-and post-NACT breast MRI for predicting breast pCR in TNBC patients.Methods Included were TNBC patients treated with NACT and surgery between 2012 and 2024.Patients were categorized into breast rCR or residual disease (rRD) and compared to pathologic response of the axilla (ypN0 vs. ypN+) and breast (pCR vs residual disease).The diagnostic performance in terms of sensitivity, specificity, positive predictive values (PPV) and negative predictive values (NPV) was determined for breast MRI in predicting ypN+.Subgroup analyses were performed for cN status.Additionally, diagnostic performance of mid-and post-NACT breast MRI for predicting breast pCR was compared. ResultsIn total, 101 cases were included of which 32.7% had breast rCR and 77.2% experienced ypN0.For predicting ypN+, the sensitivity, specificity, PPV and NPV of breast MRI was 95.7%, 41.0%, 32.4% and 97.0%.In cN0 patients, the NPV was 100% (22/22), compared to a NPV of 90.9% (10/11) in cN+ patients.Breast MRI at mid-and post-NACT predicted breast pCR with 93% vs. 83% sensitivity and 36% vs. 63 specificity. ConclusionOur results suggest that in cN0 TNBC patients, breast rCR on breast MRI may be a reliable predictor for ypN0.