Abstract P1-14-17: Study of breast cancer shrinkage modes after neoadjuvant chemotherapy with whole-mount serial sections and three-dimensional pathological and MRI reconstruction
Authors: Wang Y-S , Zhang Z-P , Liu G , Mu D-B , Sun X-Y 
Published: August 2014

Background: The main clinical goal of NAC is to down-stage the primary tumor for BCS, yet BCS after NAC has been associated with significantly higher ipsilateral breast tumor recurrences. The main reseason might be the uncertain shrinkage modes of the breast cancer after NAC. The primary objective is to observe the shrinkage modes of the primary tumor after 3 cycles and whole cycles of NAC, respectively, with whole-mount serial section (WMSS) and three-dimensional (3D) pathological reconstruction of the residual tumor. The second objective is to investigate the predictive value of 3D MRI reconstruction for the shrinkage modes of the primary tumor after NAC.

Methods: A total of 60 pts were enrolled. The first 30 pts received 3 cycles NAC and the second 30 pts received whole cycles of NAC. Breast specimens were obtained according to the original tumor border extending 3cm, and WMSS at 3mm intervals were performed. The residual tumor area were microscopically outlined on each slides. The 2D images were processed with Adobe Photoshop 9.0 and the 3D model of the residual tumor was reconstructed with the 3D-DOCTOR software. MRI were performed for the second 30 pts before, at the middle, and after NAC, respectively. The 3D MRI reconstructions at different times of NAC were compaired with the 3D pathological reconstruction to investugate its predictive value.

Results: For pts received 3 cycles of NAC, pCR was obtained in 1 case. Of the other 29 pts, honeycomb shrinkage mode was observed in 28 cases (96.6%) with no significant decrease of the histological range after NAC (p &gt; 0.05); and concentric shrinkage mode was observed only in 1 case (3.9%). More diffusive residual DCIS was observed in pts with diffusive microcalcifications on mammography before NAC than those without (76.5% vs. 7.7%, κ=0.670, p &lt; 0.01).

For pts received whole cycles of NAC, pCR and pPR were achieved in 7 (23.33%) and 23 pts (76.67%), respectively. For the 23 pts with pPR, the shrinkage modes were concentric in 10 (43.48%) and honeycomb in 13 pts (56.52%), respectively. Altogether, 17 pts (56.67%, pCR in 7 + pPR with concentric shrinkage mode in 10 pts) suitable for BCS after NAC. The 3D MRI reconstruction after NAC was highly predictive for the shrinkage modes of the primary tumor (r = 0.747, P&lt;0.001).

Whole cycles of NAC significantly improved the pCR rate and concentric shrinkage mode (both p &lt; 0.01) compaired with 3 cycles of NAC. The shrinkage modes were not significantly associated with patient age, tumor size, axillary node status, histopathological type, ER, PR, HER2, and Ki67 (all p &gt; 0.05).

Conclusions: The main shrinkage mode was honeycomb mode (96.6%) after 3 cycles of NAC, indicating that 3 cycles of NAC was not enough to down-stage the primary tumor for BCS. Whole cycles of NAC significantly improved the pCR rate and concentric shrinkage mode compaired with 3 cycles of NAC, and more than half of the patients suitable for BCS after NAC. Patients with diffusive microcalcification might not suitable for BCS after NAC. The 3D MRI reconstruction after NAC was highly predictive for the shrinkage modes of the primary tumor after NAC. WMSS and 3D pathological and 3D MRI reconstruction provided a new platform in this area.

Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P1-14-17.