Dr Cathryn Walton answers frequently asked questions regarding oestrogen receptor-positive breast cancer.
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What is oestrogen receptor-positive breast cancer?
Breast cancer is broken down into three main biological groups:
- Hormone receptor-positive – those that have oestrogen or progesterone receptors.
- HER2-positive breast cancer – those that have HER2 receptors.
- Triple-negative breast cancer – neither hormone receptor nor HER2 receptor-positive.
What is an oestrogen receptor?
A receptor is a specific site on a cell that takes up oestrogen from the bloodstream. The oestrogen then stimulates the growth and division of the cell by various mechanisms. It’s like roots of a plant; it absorbs nutrients (oestrogen) that makes the plant (cell/cancer) grow.
How is an oestrogen receptor detected?
Pathologist uses specific stains on the histology specimen to evaluate the receptors. If the stain sticks on the cell in a specific area of the cell, then the receptor is there. This is seen under the microscope. If there are oestrogenic receptors in more than 1% of cancer cells, then the cancer is considered oestrogen-positive.
What is the treatment for ER+ breast cancer?
Treatment of any breast cancer is individualised. Surgery remains the mainstay of treatment. This may be a mastectomy or lumpectomy with a sentinel node dissection. Depending on the stage and grade of cancer, you may need chemotherapy as well as radiation.
All patients with oestrogen receptor-positive breast cancer will need a form of anti-oestrogen therapy.
Because the cancer is stimulated by the absorption of oestrogen, the growth rate of the cell can be reduced by lowering oestrogen receptor activity in the body. The oestrogen positivity of this breast cancer predicts that the cancer will be sensitive to anti-oestrogen therapy.
Anti-oestrogen therapy
- Aromatase inhibitors reduce the amount of circulating oestrogen in the blood by blocking the production of oestrogen.
- Targets the oestrogen receptors:
- Selective oestrogen receptor modulators (SERMs) modulate the functioning of the oestrogen receptors.
- Selective oestrogen downregulators (SERDs) reduce the number of oestrogen receptors and sensitivity.
Are there side effects of anti-oestrogen therapy?
The treatment results in the reduced production of oestrogen or reduced number of oestrogen receptors in the body. The side effects therefore result in post-menopausal symptoms; this includs skin-, hair- and vaginal dryness, and bone pain.
With aromatase inhibitors that reduce the production of oestrogen, there may also be an effect on bone density.
With SERMs and SERDs that alter the receptor itself, there may be increased risk of blood clots as well as increased risk of uterine cancers.
Who gets ER+ positive breast cancer?
Anyone can get this type of cancer. Though it’s more common in the white population than black population, and more common in patients with high-circulating oestrogen levels. This can occur in:
- Post-menopausal patients on oestrogen-only hormone replacement therapy (HRT).
- While on oral contraception (NOT after stopping contraception).
- Intake of oestrogen in food.
It’s important to remember that hormone levels fluctuate throughout your lifetime. Circulating oestrogen level is not the only factor in the cause of hormone receptor-positive breast cancer.
Facts
- Oestrogen receptor-positive breast cancer diagnosis is the most common type diagnosed (80% of cases).
- Most common in post-menopausal women and men.
- There is improved outcome of this type of breast cancer.
- Risk of recurrence is lower in the short term; 9.9% annual risk in first five years.
- Risk of recurrence is higher in the long term (after five years after diagnosis) in comparison to other breast cancer types before and after five years. Annual risk of recurrence after five years is 5.4 – 2.8% versus 3.3% – 1.2% in other cancer types.
- When oestrogen receptor-positive breast cancer spreads, it spreads most commonly to bone, soft tissue, and reproductive organs.
MEET THE EXPERT – Dr Cathryn Walton
Dr Cathryn Walton is a clinical oncologist. In 2023, she opened her own practice, Bay Oncology, in Gqeberha, Eastern Cape with a primary focus on breast cancer, skin cancers, sarcoma, CNS malignancies, paediatric radiation, and radiation of benign conditions.
This article is sponsored by Accord Healthcare in the interest of education, awareness and support. The content and opinions expressed are entirely the doctor’s own work and not influenced by Accord in any way.
Header image by Freepik
