HR-Positive (Hormone Receptor–Positive)

HR-Positive (Hormone Receptor–Positive)

• Definition:
  
  Tumors that express estrogen receptors (ER) and/or progesterone receptors (PR) on the cancer cells. These hormone receptors allow the tumor to grow in response to hormones.
• Common in:
  • Breast cancer (the majority of breast cancers are HR-positive)
  • Some other hormone-driven cancers

Clinical Significance

• Treatment implications:
  
  HR-positive tumors generally respond to endocrine (hormonal) therapies which block hormone effects or reduce hormone levels, such as:
  • Aromatase inhibitors (letrozole, anastrozole, exemestane)
  • Selective estrogen receptor modulators (SERMs) like tamoxifen
  • Selective estrogen receptor degraders (SERDs) like fulvestrant, elacestrant
  • CDK4/6 inhibitors (ribociclib, palbociclib, abemaciclib) are often combined with endocrine therapy in advanced disease.
• Prognosis:
  
  HR-positive breast cancers tend to have a better prognosis compared to HR-negative ones but may have a risk of late relapse.

Testing

• Determined by immunohistochemistry (IHC) staining of tumor tissue.
• Usually reported as positive if ≥1% of tumor cells stain for ER and/or PR.