Neoadjuvant chemotherapy for breast cancer: correlation between the baseline MR imaging findings and responses to therapy

To retrospectively evaluate the magnetic resonance (MR) imaging findings of breast cancer before neoadjuvant chemotherapy (NAC) and to compare findings of chemosensitive breast cancer with those of chemoresistant breast cancer. The MR imaging findings before NAC in 120 women undergoing NAC were reviewed. The MR imaging findings were compared with the pathological findings and responses. A complete response (pCR) and marked response were achieved in 12 and 35% of 120 breast cancers in 120 women respectively. Breast cancers with a pCR or marked response were classified as chemosensitive breast cancer. The remaining 64 breast cancers (53%) were classified as chemoresistant breast cancer. Large tumour size, a lesion without mass effect, and very high intratumoural signal intensity on T2-weighted MR images were significantly associated with chemoresistant breast cancer. Lesions with mass effect and washout enhancement pattern were significantly associated with chemosensitive breast cancer. Areas with very high intratumoural signal intensity on T2-weighted images corresponded pathologically to areas of intratumoural necrosis. Several MR imaging features of breast cancer before NAC can help predict the efficacy of NAC.