Jeon-Hor Chen MD, Presenter: Nothing to Disclose

Garima Agrawal MD, Abstract Co-Author: Nothing to Disclose

Hon Yu, Abstract Co-Author: Nothing to Disclose

Philips Carpenters, Abstract Co-Author: Nothing to Disclose

Mehta Rita, Abstract Co-Author: Nothing to Disclose

Min-Ying Su, Abstract Co-Author: Nothing to Disclose

Orhan Nalcioglu PhD, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

et al, Abstract Co-Author: Nothing to Disclose

Pre-operative MRI is known to provide accurate disease extent of breast cancer. The role of MRI in neoadjuvant chemotherapy (NAC) response monitoring needs to be established. We evaluated the accuracy of MRI in estimating residual disease and pathological complete remission (pCR) following NAC.

From 2003 to 2006, 51 patients, 25 HER2 positive and 26 HER2 negative, were enrolled. The NAC consisted of AC followed by taxane (Pacitaxel and Carboplatin), with Trastuzumab for HER2/+ arm. The tumor size was 0.9-8.5 cm (median 2.4 cm), with 19 stage-II, 18 stage-III, and 14 stage-IV. Three follow-up MRI were performed, FU-1 and 2 during, and FU-3 after completing NAC. Response was evaluated by measuring the 2-D tumor size on the MIP. pCR was defined when no invasive cancer was present in pathology.

The serial F/U MRI allowed for accurate monitoring of tumor shrinkage by comparing to previous MRI. When the residual enhancement became equal or lower than that of normal glandular tissue, it was determined to achieve complete response. MRI diagnosed 35 cases with complete response, and the accuracy for predicting pCR was (18/19, 95%) in HER2/+, and (8/16, 50%) in HER2/- (p <0.01). The high false negative rate in HER2/- arm was attributed to small foci less than 3 mm, or scattered cancer cells. For15 partial response cases, MRI determined size (0.4-3.7 cm) was highly correlated with pathological size (0.4-6 cm), r = 0.978, p < 0.0001. The response to the AC regimen improved the pCR rate in HER2/- arm. The pCR rate in AC responder vs. non-R was 9/17, 53% vs. 0/8, 0%, p=0.007, but not different in the HER2/+ (9/11, 82% vs. 9/12, 72%).

The serial F/U MRI during NAC can monitor tumor response to each regimen. It can accurately predict pCR in HER2/+ patients and estimate the residual pathological size. MRI underestimates disease extent when residual tumor is presented as small or scattered foci.

The high accuracy of MRI for diagnosis of residual disease after NAC may facilitate the optimal surgical planning. In HER2/- patients a complete response determined on MRI should be interpreted conservatively.

Chen, J, Agrawal, G, Yu, H, Carpenters, P, Rita, M, Su, M, Nalcioglu, O, et al, , et al, , Tumor Response in Breast Cancer Patients Following Neoadjuvant Chemotherapy: Correlation of MR Imaging and Final Pathology.  Radiological Society of North America 2007 Scientific Assembly and Annual Meeting, November 25 - November 30, 2007 ,Chicago IL. http://archive.rsna.org/2007/5001800.html