Info
PR (progesterone receptor)
A molecular marker that shows whether the tumor responds to progesterone. It is interpreted together with ER to establish whether hormone therapy is suitable.
What it means
A protein present in some tumor cells that responds to the hormone progesterone. It is tested together with ER, HER2 and Ki-67 to characterise the molecular type of the tumor.
In short
A molecular marker that shows whether the tumor responds to progesterone. It is interpreted together with ER to establish whether hormone therapy is suitable.
Where you will see it
Mentioned in the immunohistochemistry (IHC) report, usually together with ER, HER2 and Ki-67. Frequently tested in breast cancer.
What it does not tell you on its own
PR on its own does not decide the treatment. It is interpreted in context with ER, HER2, Ki-67, stage and grade.
Questions for your doctor
- Am I PR positive or negative?
- What does the ER/PR combination mean for my treatment?
- Does it influence the type of hormone therapy?
Related terms
The terms below often appear alongside this one. Each definition is right here, so you do not have to look elsewhere.
- Immunohistochemistry
- A laboratory technique that uses antibodies to detect specific proteins in tumor cells. It helps establish the exact type of cancer and choose the right treatment, especially in breast, colon and lung cancers.
- ER (oestrogen receptor)
- A protein present in some tumor cells that responds to the oestrogen in the body. ER positive tumors can be stimulated by oestrogen — but they can also respond to hormone therapy.
- HER2
- A protein that can be present in large amounts on the surface of some cancer cells. HER2 positive means that the tumor may respond to specific biological treatments that target this protein.
- Hormone therapy
- A treatment that blocks or reduces the effect of certain hormones that can drive the growth of some tumors, such as some breast or prostate cancers. It is usually given over the long term and is part of the overall cancer treatment plan.
Other terms in “Diagnosis”
Glossary definitions are written for patients by the OncoDots team and go through internal medical review. They explain terms; they do not establish a diagnosis and do not recommend a treatment.