Key clinical point: Adjuvant endocrine therapy (ET) significantly reduces the incidence of distant metastasis in patients with estrogen receptor-positive (ER+)/human epidermal growth factor receptor 2-negative (HER2−) T1a/bN0M0 breast cancer (BC).
Major finding: The 9-year cumulative incidence of distant metastasis was significantly lower in patients who did vs did not receive adjuvant ET (1.5% vs 2.6%; adjusted subdistribution hazard ratio 0.54; P = .027), with the risk factors for distant metastasis being mastectomy (P = .022), no prior receipt of ET (P = .027), lymphatic invasion (P = .004), and higher nuclear grade (P = .047).
Study details: Findings are from a multicenter cohort study including 4758 patients with ER+ /HER2− T1a/bN0M0 BC who underwent surgery, of whom 3991 patients were administered adjuvant ET.
Disclosures: This study was partly supported by the National Cancer Center Research and Development Fund and the Practical Research for Innovative Cancer Control, Japan. The authors declared no conflicts of interest.
Source: Sasada S et al. Prognostic impact of adjuvant endocrine therapy for estrogen receptor-positive and HER2-negative T1a/bN0M0 breast cancer. Breast Cancer Res Treat. 2023 (Sep 9). doi: 10.1007/s10549-023-07097-6