The significance of highlighting the oestrogen receptor low category in breast cancer

Abstract

The latest ASCO/CAP guideline has recommended to report oestrogen receptor (ER) low cases (ERlo; 1–10%) as “ER low positive category”, prompting us to compare the clinicopathologic features, biomarkers, survival and treatment of the ERlo cases with other subgroups (ER negative (ERneg) and ER high (ERhi)). ERlo cases revealed more similar clinicopathologic and biomarker profiles (including younger age, larger tumour, high proliferation, HER2 and basal markers expression) to ERneg than ERhi cancers. The ERlo cases receiving hormonal therapy showed a similarly poor outcome as ERneg cancers. However, majority of ERlo cases were downstaged to stage I in the 8th AJCC pathological prognostic staging, highlighting a risk of potential under treatment. Overall, our data highlighted the differences of ERlo from other ERpos cases and their management should be considered separately.

Estrogen receptor‐low breast cancer: Biology chaos and treatment paradox

“…Compared with ER‐high cases, ER‐low cases were associated with higher grade, more necrosis, more stromal tumor‐infiltrating lymphocytes, and higher expression of Ki67, HER2, EGFR, and CK5/6. Compared with ER‐negative cases, ER‐low cases were associated with higher PR but lower grade, lower expression of CK5/6 and CK14 [ 53 ]. These findings indicated distinct and heterogeneous behavior of ER‐low tumors, with some resembling ER‐negative tumors biologically.…”

Clinical characteristics and survival outcome of patients with estrogen receptor low positive breast cancer

“…However, the benefit of endocrine therapy for tumors staining ER positive 1%–10% (ER-low) remains controversial. Recent studies suggested ER-low patients as a heterogeneous category, whose clinical behaviors and molecular profiles appears more similar to those of ER-negative breast cancers [ [10] , [11] , [12] , [13] ]. Due to the low frequency of this subgroup, there is limited evidence on endocrine responsiveness of ER-low patients.…”

Effect of Estrogen Receptor Expression Level and Hormonal Therapy on Prognosis of Early Breast Cancer

“…It is suggested that treatment options for ER − tumors may be appropriate for some ER low tumors; however, endocrine responsiveness of primary breast cancer patients with low ER expression needs to be further explored in prospective studies. 20 This study has certain limitations. First, the study was limited by its retrospective design, and treatment options were not assigned in a randomized manner.…”

“…Compared to ER high , ER low breast cancer is associated with younger age, advanced stage, larger tumor size, higher HER2 expression, and lower PR expression. 19,20 When morphologically analyzed, ER low tumors exhibit features previously described for basal-like and triple-negative tumors, including higher grade, higher proliferation index, sheet-like growth pattern, intratumoral lymphocytic in ammatory in ltrate, and necrosis. 12 In our current study, we focused speci cally on early stage breast cancer, a novel approach not presented in previous literature.…”

“…This result was in concordance with previous literature. 17,19,20 Although limited data is available on the survival outcome of ER low breast cancer, a few previous studies showed that ER low patients exhibit signi cantly worse disease-free and overall survival rates compared to ER high patients, but similar to those who are ER − . 11,21,22 In the current study, the ER low group had a slight, but not statistically signi cant, survival bene t over the ER − group.…”