Taxane-based combinations as adjuvant chemotherapy for node-positive ER-positive breast cancer based on 2004–2009 data from the Breast Cancer Registry of the Japanese Breast Cancer Society

Background: Adding taxane to an anthracycline-based regimen improves survival in node-positive breast cancer patients, as shown by clinical trials and meta-analyses. However, no studies have analyzed the number of metastatic lymph nodes in patients with estrogen receptor (ER)-positive cancer. This study investigated whether adding a taxane to an anthracycline-based regimen improved prognosis in node-positive, ER-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer patients in a real-world setting. Methods: Using Japanese Breast Cancer Society registry data, we compared disease-free survival (DFS) of patients with ER-positive, HER2-negative breast cancer, excluding those receiving neoadjuvant chemotherapy, between those who received an anthracycline-based regimen followed by a taxane-based regimen (A + T) and those who received only an anthracycline-based regimen (A w/o T), stratified by lymph node status. A Cox proportional hazards model was used to evaluate DFS in both groups. Results: There were 4566 eligible patients with ER-positive, HER2-negative breast cancer. During the median follow-up period of 60 months, there were 481 recurrences and 149 deaths. There was no significant difference in DFS between the A + T and A w/o T groups among patients with 1–3 positive nodes, while there was a significant difference among patients with ≥ 4 positive nodes. Conclusions: In patients with ER-positive, HER2-negative breast cancer, adding taxane to an anthracycline regimen did not improve DFS in patients with metastasis in 1–3 lymph nodes. We considered that the group without the addition of taxane might be present in patients with ER-positive, HER2-negative lymph node metastases.