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 >20 mm.

Conclusion

Contrast enhanced MRI enabled fairly accurate measurement in NAE as well as in NAC.