False-positive MRI Findings in Breast Cancer After Neoadjuvant Chemotherapy and Correlation Between Tumor Response Patterns and HER2 Status

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Avdan Aslan A., Erdemli S., ERDOĞDU İ. H., Gultekin S., URAS C., Tokat F., ...Daha Fazla

ACTA ONCOLOGICA TURCICA, cilt.56, sa.2, ss.97-105, 2023 (TRDizin)

Özet

INTRODUCTION: To demonstrate false-positive MRI findings after neoadjuvant chemotherapy (NAC) in patients with pathologic complete response (pCR) and investigate the correlation between post-NAC MRI findings and tumor response patterns based on human epidermal growth factor receptor 2 (HER2) status. METHODS: This retrospective multicenter study enrolled 118 patients with breast cancer who received NAC and achieved pCR. Tumors were evaluated with MRI pre- and post-NAC. MRI evaluation included lesion characteristics, kinetic curve analysis, background parenchymal enhancement (BPE), and post-NAC changes of MRI features. Tumor response patterns were also assessed and categorized based on MRI findings. Tumor response patterns and post-NAC MRI findings were correlated with HER2 status. RESULTS: The residual MRI findings following NAC differed significantly between HER2+ and HER2− groups (p=0.02). The most frequent false-positive MRI finding was focus and foci in HER2+ tumors, whereas non-mass enhancement (NME) in HER2− group. The presence of ductal carcinoma in situ (DCIS) and fibrosis in surgical pathology is significantly associated with NME on post-NAC MRI (p<0.001). Axillary pCR was achieved significantly higher in the HER2+ group (p=0.04). DISCUSSION AND CONCLUSION: Although MRI is considered the most reliable method for evaluating tumor response after NAC, over and underestimation is still possible. This study revealed that tumor response patterns and post-NAC MRI findings differ according to HER2 status. The diagnostic accuracy of post-NAC MRI is evolving by understanding the underlying mechanisms and tumor biology.