Survival outcome of adjuvant endocrine therapy alone for patients with lymph node-positive, hormone-responsive, HER2-negative breast cancer.

Background/objective: The prognosis of hormone receptor-positive and HER2-negative breast cancer is better than that of other subtypes. Current guidelines recommend chemotherapy for N1 breast cancer patients. However, this has the possibility to be over-treatment.

Methods: This was a retrospective study of 18,549 patients who were surgically treated for invasive breast cancer, at a single center in South Korea, between January 1993 and December 2012. N1 stage breast cancer patients who were hormone receptor-positive and HER2-negative were enrolled, and propensity score matching was performed to compare patients treated with anti-hormonal therapy alone (N = 83) and those treated with chemotherapy followed by anti-hormonal therapy (N = 85).

Results: In survival analysis, the survival parameters of the endocrine therapy-only group and the chemotherapy with endocrine therapy group were respectively 96.1% and 94.0% for 5-year recurrence free survival (RFS), 89.6% and 94.0% for 10-year RFS, 97.4% and 94.0% for 5-year distant metastasis-free survival (DMFS), 93.2% and 94.0% for 10-year DMFS, 98.7% and 98.8% for 10-year breast cancer-specific survival (BCSS), and 98.7% and 98.8% for 10-year overall survival (OS). There were no significant differences in RFS (p = 0.871), DMFS (p = 0.491), BCSS (p = 0.569) and OS (p = 0.731) between the two groups.

Conclusion: Several patients with clinicopathologic features like hormone receptor positivity and HER2 negativity can avoid chemotherapy even with lymph node metastasis. Future studies with a long-term follow-up and a larger number of patients are required for validating our results.