Is there a correlation between estrogen receptor expression level and early breast cancer survival? A Retrospective...

The optimal cut-off of ER-positivity is still debatable; however, adjuvant hormonal therapy is usually given if ER expression = 1%. The present study aims to assess clinicopathological features and survival outcome of patients with low compared to higher ER expression level.

In this retrospective, we checked nonmetastatic hormonal receptors-positive, HER2 negative breast cancer patients who presented to three Hospitals in Egypt and Saudi Arabia between 2020-2022. Different clinicopathological factors and data of relapse were checked in patients' medical records. These data were compared in patients with ER-Low (1-10%) Vs. ER-High (>10%) expression level.

We included 419 patients who met the eligibility criteria of the study. Only 3.3% of patients had ER-Low. Compared to ER-High group, the ER-Low expression were more likely to have grade 3 tumours (64.3% vs. 21.0%, p=<0.0001), PR-negative (64.3% vs. 16.3%, p= <0.0001). Furthermore, younger age (= 50 years) was more frequent in ER-Low group compared to ERHigh patients (71.4% vs. 42.5%, respectively, p=0.032). Likewise, ER-High patients were more likely to have high ER-staining intensity (74.1% vs. 0.0%, p<0.0001). Disease free survival (DFS) was numerically improved in patients with ER-High, but without statistical significance. After adjustment of different clinicopathological prognostic factors, DFS benefit in ER-High group was more definite (HR=3.59, 95% CI 1.11-11.55, p=0.032).

ER-low (1-10 %) expression was rare in the study group. Low ER expression was linked with more aggressive features at diagnosis and seems to have worse DFS which was more pronounced after adjustment for different clinic-pathological factors.