Estrogen receptor negative status [ER-]

This diagnosis indicates that a tumor, typically breast cancer, does not express estrogen receptors. This lack of estrogen receptor expression means the cancer cells are not stimulated to grow by estrogen. It has significant implications for treatment planning, as hormone therapies targeting estrogen pathways will not be effective.

This code is used when pathology reports confirm the absence of estrogen receptors in a malignant tumor. It is crucial for documenting the biological characteristics of a cancer, particularly for breast cancer patients. This finding guides oncologists in selecting appropriate treatment regimens, such as chemotherapy instead of endocrine therapy.

• Always base the use of this code on definitive pathology results.
• Do not assign this code if the estrogen receptor status is unknown or equivocal.
• This code is typically assigned as a secondary diagnosis, following the primary malignancy code.