The Prognostic Effect of Changes in Tumor Stage and Nodal Status After Neoadjuvant Chemotherapy in Each Primary Breast Cancer Subtype.

BACKGROUND: Although the prognostic value of pathologic complete response (pCR) after neoadjuvant chemotherapy (NAC) depends on the intrinsic subtype of breast cancer, it is not clear whether chemosensitivity itself, shown by a decreasing tumor burden after NAC, contributes to improved prognosis in primary breast cancer patients, especially in patients with non-pCR. The aim of this study was to assess the prognostic effect of changes in tumor stage or nodal status after NAC in each primary breast cancer subtype.

PATIENTS AND METHODS: We assessed 719 consecutive patients with primary breast cancer who underwent surgical resection after NAC between 2001 and 2010. The patients were divided into 5 subtypes according to their hormone receptor (HR) status, HER2 status, and nuclear grade (NG; 1/2 = low, and 3 = high).

RESULTS: In patients with HR-positive (HR+ )/HER2- /NG-low tumors, regardless of change in tumor size, the loss of node positivity after NAC significantly improved disease-free survival (DFS). In patients with HR+ /HER2- /NG-high tumors, achievement of tumor downstaging as well as the loss of node positivity improved their DFS. In patients with HR- /HER2- tumors, tumor downstaging and the loss of node positivity significantly improved DFS, despite a non-pCR. In contrast, in patients with HER2+ tumors, changes in tumor stage or nodal status were not associated with prognosis unless pCR was achieved.

CONCLUSION: Our results revealed that changes in tumor stage and nodal status after NAC might be prognostic markers in patients with HR+ /HER2- /NG-high tumors or HR- /HER2- tumors, even if there are residual tumors in the breast.