How much variability can you see in levels of ER/PR expression between the primary tumor and a metastasis to make you reconsider if it's a second primary?

One example is the original breast cancer ER high 90%, PR mod to high 40%, Her2 negative. A liver metastasis diagnosed 2 years later showed ER low to moderate pos 40%, PR negative, and Her2 negative.

Would this impact therapy decisions and/or genetic screening (eg now diagnosed with two primaries as one criteria)?

Answer from: Medical Oncologist at Academic Institution

Expression of estrogen, progesterone receptors can vary over time and between primary and metastatic sites in approximately 10-15% of cases based on literature. It can also be affected by technical aspects such as cold ischemia time, negative/positive controls used and pathologist interpretation of ...

Comments

Medical Oncologist at Maricopa Integrated Health Svcs
Very insightful answer

Medical Oncologist at Covenant Cancer Treatmt Center
Agree with above but add the following. Treatment ...

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How much variability can you see in levels of ER/PR expression between the primary tumor and a metastasis to make you reconsider if it's a second primary?

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