Diagnostic performance of MRI in predicting pathological response in patients with triple-negative breast carcinomas undergoing neoadjuvant chemotherapy and immunotherapy.

OBJECTIVE

Triple-negative breast cancer (TNBC) is an aggressive subtype of invasive breast carcinoma with limited treatment options. Neoadjuvant chemotherapy (NAC) is a standard approach, allowing less extensive surgeries and enabling in vivo assessment of treatment response. MRI plays a key role in evaluating this response. Recently, the addition of immune checkpoint inhibitors has transformed the treatment landscape. This study aims to compare the diagnostic performance of MRI in predicting the pathological response in patients with invasive TNBC undergoing NAC with and without immunotherapy.

MATERIALS AND

METHODS

This retrospective single-center study included female patients with TNBC who underwent NAC or NACI followed by surgery between 2021 and 2024. All patients underwent two MRIs: one before treatment (pretreatment) and one after treatment (preoperative). Radiologic complete response (rCR) was defined as the absence of abnormal enhancement at preoperative MRI. Pathological response was assessed by the Residual Cancer Burden (RCB) index, with pCR defined as RCB-0. MRI performance was calculated using pathological response as the gold standard.

RESULTS

A total of 111 patients were included: 59 in the NAC group and 52 in the NACI group. The NACI group showed higher rates of rCR (75% vs. 44.1%; p < 0.001) and pCR (67.3% vs. 47.5%; p = 0.025). MRI demonstrated superior sensitivity (94.3% vs. 67.9%), accuracy (84.6% vs. 72.8%), and AUC (0.736 vs. 0.602) in the NACI group.

CONCLUSION

MRI demonstrated good diagnostic performance in predicting pCR in patients with TNBC treated with NAC associated with immunotherapy.

KEY POINTS: Question Triple-negative breast cancer (TNBC) is an aggressive subtype with limited treatment options. NAC is standard, but the addition of immunotherapy has shown improved outcomes in early TNBC. Findings MRI demonstrated higher sensitivity (94.3% vs. 67.9%) and accuracy (84.6% vs. 72.8%) in predicting pCR in patients with TNBC treated with NAC associated with immunotherapy, with an AUC of 0.736 compared to 0.602. Clinical relevance In patients with TNBC treated with neoadjuvant chemotherapy and immunotherapy, MRI demonstrates improved accuracy in predicting pathological complete response, supporting its use as a noninvasive tool to guide treatment personalization and potential surgical de-escalation.