MRI evaluation of residual tumor size after neoadjuvant endocrine therapy vs. neoadjuvant chemotherapy

Aim: To investigate if there is any difference in evaluation of residual tumor size after neoadjuvant chemotherapy (NAC) and neoadjuvant endocrine therapy (NAE). Methods: Seventy-eight tumors in 57 patients were prospectively enrolled. Residual tumor sizes in contrast-enhanced MRI after NAC and NAE were compared with those measured on surgical specimen by using linear regression analyses. The line slope values >1 indicates overestimation by MRI. Differences in types of shrinkage patterns: concentric shrinkage (CS) and dendritic shrinkage (DS) were also investigated. Results: Fifty lesions were treated with NAC and 28 lesions were treated with NAE. Shrinkage patterns were CS in 33 lesions and in 45 lesions. The slopes values were 0.75 (R = 0.92) and 0.70 (R = 0.90) for NAC and NAE, respectively, and no significant difference was observed (p = 0.46). However, they were 1.02 (R = 0.92) and 0.68 (R = 0.92), respectively for CS and DS with significant difference (p < 0.01). The difference between CS and DS was found only in a subgroup with size by MRI >20mm. Conclusion: Contrast enhanced MRI enabled fairly accurate measurement in NAE as well as in NAC. (C) 2011 Elsevier Ireland Ltd. All rights reserved.