Estrogen Receptor Assay (ERA)
A laboratory test of breast cancer tissue to determine the responsiveness of the tumor to hormone manipulation, endocrine therapy or removal of the ovaries. About 55% of ER positive tumors will respond to endocrine therapy. Tumors which are negative for estrogen receptors rarely respond to hormone manipulation. The unit of measurement is femtomoles (fmoles) per milligram of tumor.
Types of ERA:
Negative: 3 fmoles or less. ERA may not be performed if tumor is less than 1.0 cm in size or if the tumor is in situ.
Progesterone Receptor Assay (PRA)
A laboratory test of breast cancer tissue to determine the responsiveness of the tumor to endocrine therapy or to removal of the ovaries. Progesterone receptor assay increases the reliability of estrogen receptor assay results: a positive progesterone receptor assay indicates greater likelihood that the patient will respond to hormone therapy. The unit of measurement is femtomoles (fmoles) per milligram of tumor.
Types of PRA:
Quantified (measured in femtomoles or fmoles)
A qualitative measurement of the observed number of hormone responsive cells, reported as positive or negative.
Negative: 5 fmoles or less. Test may not be performed if tumor is less than 1.0 cm in size or if tumor is completely in situ.
Other Breast Cancer Tumor Markers
Presence is associated with multidrug resistance.
Distinguishes node-negative patients who may recur (and therefore should receive adjuvant chemotherapy) from node-negative patients who probably will not recur. Elevation indicates a poorer prognosis.
C-erb B-2 (also called HER-2 or neu oncoprotein)
Associated with larger sized tumors, shorter relapse time and lower survival rate.
C-myc DNA amplification
Elevated (amplified) in breast cancers in older women.
Int-2 DNA Amplification
Elevation (amplification) associated with recurrence of tumor.
Go to the Tumor Markers page of the Diagnostic Tests module for more information.