Progesterone Receptor (PR) For Breast Neoplasm
- The paraffin blocks of the breast cancer tissue needed for the cytochemical method.
- There are immunocytochemical and immunochemical methods.
Purpose oh the test (Indications)
- PR is done to see the sensitivity to hormone therapy in the case of breast cancers.
- PR gives the prognosis of breast cancers.
- Progesterone receptor is a specific cellular protein with high affinity and specificity for progesterone hormone.
- The progesterone receptor protein is found in the target tissue like the breast, uterus, pituitary gland, and hypothalamus.
- Progesterone stimulates the cells through the progesterone receptor.
- A reduction in the blood progesterone level reduces the biochemical activity of this cell.
- This is the basis for the treatment of breast cancer by antihormone therapy,
- PR positive breast cancer more responsive than PR negative cases.
- Postmenopausal women breast cancers are more PR positive than young women.
- Mechanism of the anti-hormone therapy where the drug blocks the site of Progesterone hormone and there is no signal for cell proliferation.
Reading of the immunocytochemistry slides:
- PR receptor stain in the nucleus (the color is brown).
- Negative = < 5 % of the cells are positive for the PR receptors.
- Positive = > 5 % of the cells stain for the PR receptors.
- Carcinoma of the breast shows 60 % positivity.
- Approximately 2/3 of the cases show a response to hormone therapy.
- PR negative cases, 90% do not respond to hormone therapy.
Response to anti-hormone therapy
|ER||PR||Response to hormones|