by Chuanxu Luo, Xiaorong Zhong, Yu Fan, Yanqi Wu, Hong
Zheng, Ting Luo
The Breast: VOLUME
63, P24-28, JUNE 01, 2022
Background
The benefit of endocrine therapy for patients with estrogen
receptor (ER)-low (1%–10%) positive breast cancer is a matter for debate. We
aimed to compare the clinical characteristics and survival outcome of ER-low
patients with ER-high (＞10%)
positive patients and ER-negative patients.
Methods
From the breast cancer database of our institution, we
identified 5466 patients with known ER status who were diagnosed with
early-stage breast cancer between January 2008 and December 2016. Variables
associated with initiation of endocrine therapy were identified using
multivariate logistic regression model. According to ER status, all patients
were classified into ER-low (1%–10%), ER-high (>10%) and ER-negative
subgroups. Fine and Gray competing risks regression was performed to compare
the survival outcome of three subgroups.
Results
Age at diagnosis, ER status and progesterone receptor (PR)
status were identified as correlates of initiation of endocrine therapy. ER-low
patients were more likely to have advanced, PR-negative, human epidermal growth
factor receptor 2 (HER2)-positive or grade Ⅲ
disease compared to ER-high patients. Similar to ER-negative patients, ER-low
patients presented increased rate of locoregional recurrence (LRR), distant
recurrence (DR) and breast cancer mortality (BCM) than ER-high patients.
Endocrine therapy showed nonsignificant trends toward lower LRR, DR and BCM in
ER-low patients.
Conclusion
Similar to ER-negative patients, ER-low patients had more
aggressive clinical characteristics and worse survival outcome than ER-high
patients. ER-low patients appeared to benefit less from endocrine therapy.
Randomized studies are needed to further explore the endocrine responsiveness
of ER-low patients.
