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

Changes in tumor stage and nodal status might have different prognostic effects in patients with each subtype of breast cancer. Tumor downstaging and loss of node positivity after neoadjuvant chemotherapy improved prognosis regardless of non-pathologic complete response (pCR) in patients with hormone receptor (HR)-positive (HR ⁺ )/HER2 ⁻ /high nuclear grade or HR ⁻ /HER2 ⁻ tumors. In contrast, in patients with HER2 ⁺ tumors, only achievement of pCR was a prognostic factor. 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.