by Yuxin Xie, Libo Yang, Yanqi Wu, Hong Zheng, Qiheng Gou
The Breast: Published: September 29, 2022
Background
Little is known about the benefits of adjuvant endocrine
therapy (ET) in low ER-positive breast cancer (1%–10%) patients. We analyzed
the association between ET and breast cancer-specific survival (BCSS) in these
patients with respect to the regimen and the duration of ET.
Methods
Patients were classified into three groups based on the
regimen and duration of ET. The regimens included aromatase inhibitor (AI)
monotherapy or sequential tamoxifen followed by an AI (AI/T + AI), or
only tamoxifen and no ET. The duration of ET included 2–3 years and >3
years. Multivariate Cox regression analysis was employed to calculate the
hazard ratios (HRs) with 95% confidence intervals (CIs).
Results
Of the 10,696 patients diagnosed with breast cancer between
2010 and 2020, 407 women were identified with ER-low positive disease and met
the inclusion criteria. During a median follow-up of 5.2 years, patients who
received ET improved BCSS. Of them, those with AI/T + AI had
increased BCSS compared to patients without ET, after adjusting for
demographics and tumor characteristics, especially in ER-low/HER-2-positive
breast cancer. After additional adjustment for treatment mode, the association
maintained a similar trend. Patients who received >3 years of ET was
associated with a better DFS. There was no significant difference in BCSS
between patients with 2–3 years and >3 years of ET.
Conclusion
For ER-low patients, findings suggest that ET with
AI/T + AI may be a reasonable treatment alternative. This effect
should be assessed in randomized studies.
