3D-MR mammography-guided breast conserving surgery after neoadjuvant chemotherapy: clinical results and future perspectives with reference to FDG-PET.

BACKGROUND: Three dimensional MR Mammography (3D-MRM) can detect tumor extension more accurately than mammography or ultrasound. There are two shrinkage patterns observed by 3D-MRM after neoadjuvant chemotherapy. Concentric shrinkage is a good indication for breast conserving surgery. On the other hand, a dendritic pattern was represent ductal spread. Therefore, we developed MRM guided mapping to aid BCS for tumors showing a dendritic pattern.

METHODS: Fifteen patients consisting of 8 stage II (T > 3.5 cm) cases and 7 stage IIIa cases aged 39 to 61 years (mean 47-8 years) were treated with AT neoadjuvant chemotherapy with the aim of performing breast conserving surgery. All patients were examined by 3D-MRM before and after neoadjuvant chemotherapy. Breast conserving surgery indications were determined by tumor volume reduction and shrinkage patterns on 3D-MRM. Supine position mapping using MRM was performed for dendritic type tumors. FDG-PET was simultaneously performed for one case with bilateral breast cancer.

RESULTS: Breast conserving surgery was performed for 13 of the 15 cases. One case underwent re-operating and mastectomy because of a positive margin. One case had microscopically positive margin and received boost radiation. Therefore, 11 of 15 cases (73.3%) underwent BCS and achieved negative margins under MRM guidance. PET scanning can detect residual tumor and occult metastasis but it is not suitable for mapping because of its spatial resolution.

CONCLUSIONS: 3D-MRM is a useful modality to select appropriate cases for breast conserving surgery after neoadjuvant chemotherapy. FDG-PET can also detect residual tumor or occult metastasis but it may not be suitable for mapping. Because both examinations have potential, further evaluation of their clinical efficacy is necessary.