E. Shyam P. Reddy, Professor and Director of the Cancer Biology Program at Morehouse School of Medicine, shared on LinkedIn:
“Research from the Karolinska Institute in Sweden shows assessing whether breast cancer tumors are estrogen receptor (ER) positive or not is more accurately measured as a spectrum rather than just classifying them as positive or negative.
The researchers used a percentage method to classify whether tumors were ER positive or not and found that women who had ER positivity of 59% or lower had significantly worse outcomes when given standard therapy for ER positive breast cancer than those with 60% or higher positivity.
‘For many years, breast cancer has been classified as either ER-positive or ER-negative, with ER positivity typically defined using a one percent or 10% cutoff. However, in routine clinical practice we often see tumors that fall between the two ends of the spectrum,’
lead investigator Balazs Acs, associate professor at the Karolinska, told Inside Precision Medicine.
‘ER expression appears to behave as a continuum rather than a simple positive-versus-negative biomarker.’
ER positive breast cancer, where the cancer feeds off estrogen, makes up as much as 80% of all breast cancer cases. Knowing ER status is important as it indicates whether a patient will respond to hormone blocking treatment, the standard therapy for this kind of cancer.
In this study, published in The Lancet Regional Health – Europe, 75,211 women with breast cancer diagnosed in Sweden between 2007 and 2023 were included. Acs and colleagues measured the percentage ER positivity of their tumors and classified the participants as:
- ER-zero (0%),
- ER-low (1-9%),
- ER-mild (10-29%),
- ER-moderate (30-59%),
- ER-high (60-100%).
‘Our study is, to our knowledge, the first large nationwide population-based analysis to comprehensively evaluate patient characteristics, treatment patterns, survival, and molecular features across the entire ER spectrum,’ –Acs.”
Other articles about breast cancer on OncoDaily.