Diffusion-weighted MR Imaging In Assessing Pathological Response Of Tumor In Breast Cancer Subtype To Neoadjuvant Chemotherapy

PurposeTo investigate the efficacy of diffusion-weighted imaging (DWI) for reflecting and predicting pathological tumor response in breast cancer subtype to neoadjuvant chemotherapy.Materials and MethodsThe retrospective study included 176 patients with breast cancer underwent MRI examinations before and after NAC prior to surgery. The pre-and post-NAC apparent diffusion coefficient (ADC) value of tumor was measured respectively on diffusion-weighted imaging (DWI). The pathological response was classified into either as a complete response (pCR) or as a non-complete response (pNCR) to NAC with Miller & Payne system. The relationship between the ADC value and the pathological response was assessed according to intrinsic subtypes (luminal A, luminal B, HER2-enriched and triple negative) defined by immunohistochemical features.ResultsMultiple comparisons respectively showed that pre-NAC and post-NAC ADC were significantly difference among four subtypes (P< 0.001). After the comparison between two different subtypes, the pre-NAC ADC value of the triple-negative and HER2-enriched subtypes were significantly higher than luminal A (P<0.001 and P<0.001) and luminal B subtype (P<0.001 and P=0.009), and the post-NAC ADC of triple-negative subtype was significantly higher than the others (P< 0.001). The pre-NAC ADC of pCRs was significantly lower than that of pNCRs only in the triple-negative subtype among four subtypes (P<0.001), and the post-NAC ADC of pCRs was significantly higher than that of pNCRs in each subtype (P<0.001).ConclusionDWI appears to be a promising tool to determine the association of pathological response to NAC in breast cancer subtypes.