De‐escalation of five‐year adjuvant endocrine therapy in patients with estrogen receptor‐low positive (immunohistochemistry staining 1%‐10%) breast cancer: Propensity‐matched analysis from a prospectively maintained cohort

Abstract

BACKGROUND:The standard 5 years of endocrine therapy has demonstrated additional benefits compared with short-term (2-3 years) treatment in patients with estrogen receptor (ER)-positive breast cancer; however, data specific to ER-low positive breast cancer (1%-10% by immunohistochemistry) are limited, and it is unclear whether long-term treatment is still necessary for this subgroup. METHODS:The authors used the prospectively maintained Breast Surgery Database of Fudan University Shanghai Cancer Center for this propensitymatched analysis. The primary end point was disease-free survival. Multivariate Cox regression analysis and propensity score-matching methods were used to minimize bias. Hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated. All statistics were 2-sided. RESULTS: From 2012 to 2017, 22,768 consecutive women had pathologically confirmed, early stage breast cancer, and 1013 (4.45%) were identified with ER-low positive disease. Among these, 634 patients met the inclusion criteria and were divided into 3 groups: those who received no endocrine therapy (n = 89), those who received 2 to 3 years of endocrine therapy (n = 185), and those who received approximately 5 years of endocrine therapy (n = 360). At a median follow-up of 65 months, there was no significant difference in disease-free survival between patients who received 2 to 3 years and 5 years of endocrine therapy (HR, 0.82; 95% CI, 0.51-1.33; P = .43). The findings were consistent after multivariate Cox analysis of the propensity score-matched samples (5 vs 2-3 years of treatment: HR, 0.74; 95% CI, 0.41-1.31; P = .30). CONCLUSIONS: Short-term endocrine therapy for 2 to 3 years might be an alternative for patients who have ER-low positive breast cancer instead of the standard 5 years of treatment.

Characteristics and Prognosis of Estrogen Receptor Low-Positive Breast Cancer

“…In the present study, ER low cases constituted 2% (46/2,309) of all IBC cases and 2.8% (46/1,666) of ER-positive IBC cases, which is consistent with previous studies that reported ER low cases accounted for 2%–5.1% of all IBC and 2.5%–7.4% of ER-positive IBC cases [ 6 7 9 13 14 15 ]. Some studies [ 9 13 ] have defined ER low as 1%–9% positive staining instead of 1%–10% (the ASCO/CAP definition).…”

“…These results support the notion that hormone therapy has limited benefits for ER low breast cancer patients. Cai et al [ 15 ] recently reported that short-term endocrine therapy for 2–3 years might be an alternative for patients with ER low breast cancer instead of standard 5 years of treatment because there was no significant difference in DFS between the 2 groups. We did not observe differences in DFS of patients with ER low according to hormone therapy, although the comparison was made with a small number of patients.…”

Biodegradable Silk Fibroin Nanocarriers to Modulate Hypoxia Tumor Microenvironment Favoring Enhanced Chemotherapy

“…While the 5-year survival outcome in traditional antitumor modalities has clinical progress, the mortality in patients with advanced tumors remained undiminished owing to metastasis and recurrence (Zhang et al, 2016;Zhang et al, 2017;Zhang et al, 2018a;Zhang et al, 2020a;Cai et al, 2022). Hypoxic tumor microenvironment (TME) is gradually recognized as an essential factor in tumor progression, especially in multidrug resistance, radiosensitivity, immunologic escape, and metastasis (Jiang et al, 2020;Jin et al, 2021).…”

Abbreviated endocrine therapy duration for low estrogen receptor‐positive breast cancer: The counter to extended endocrine therapy

“…Other limitations include the lack of quantification of progesterone receptor (PR) status. Although the study includes positive or negative PR status (see their Table 1 16 ), quantification was not reported, and PR status was not included in propensity matching although PR expression is a known prognostic variable. 3,17 The study does not address the question of whether PR status influences the decision for duration of endocrine therapy.…”

“…In this issue of cancer, Cai et al 16 take an important look at the topic of endocrine therapy for ER‐low tumors. Theirs was a single‐center, prospective study of 634 eligible patients using propensity‐matched analysis to compare DFS in patients with ER‐low breast cancer who received no endocrine therapy, 2 to 3 years of endocrine therapy, or 5 years of endocrine therapy.…”