This study was performed to evaluate the utility of initial MRI in predicting the extent of residual disease following neoadjuvant chemotherapy (NAC). The study population consisted of 70 patients with breast cancer (unilateral, n=69; bilateral, n=1) (mean age 51 years) who underwent magnetic resonance imaging (MRI) with gadolinium enhancement both before and after NAC. Basic NAC was comprised of cyclophosphamide, pirarubicin, and 5-fluorouracil. MRI features were compared with pathological diagnosis following surgery. MRI features of breast cancer before NAC were classified as either solitary nodular (SN) (n=33) (47%), or multiple nodular and/or unlocalized dendritic (MN/UD) (n=38) (53%). MRI typing was independent of NAC in 68 tumors (SN, n=32; MN/UD, n=36) (96%, p<0.0001). All except one of the 33 SN tumors (97%) displayed negative margins. In addition, 5 of the 33 SN tumors (15%) displayed pathological complete response (pCR). Conversely, all 5 requiring total glandectomy due to wide infiltration and all except one of the 17 (94%) displaying positive margins necessitating extended resection were classified as MN/UD. Only SN-type tumors on initial MRI have the possibility of pCR after NAC. MN/UD tumors could possess margins necessitating expanded excision or total glandectomy. Morphological concepts based on MRI can prove useful in surgical planning and predicting the extent of residual disease after NAC.

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