1. How hormones can affect breast cancer
Some breast cancers use hormones in the body to help them grow.
This type of breast cancer is called hormone receptor positive breast cancer.
What are hormones?
Hormones are substances made naturally in the body. They act as ‘messengers’ that tell organs or tissues to carry out various functions.
Oestrogen is the main hormone that helps some breast cancers to grow.
Progesterone is another hormone that may affect some breast cancers.
What are hormone receptors?
Breast cells contain special proteins called hormone receptors. These receptors ‘receive’ messages from hormones in the body and respond by telling the cells what to do.
The hormone receptors found in breast cells are known as and .
2. Oestrogen receptor positive (ER-positive) breast cancer
Oestrogen is a hormone that plays an important role in the female reproductive system.
Sometimes breast cancer cells contain oestrogen receptors. This is called oestrogen receptor positive or ER-positive breast cancer.
When oestrogen receptors are found in breast cancer cells, this can help the breast cancer to grow.
All breast cancers are tested for oestrogen receptors using tissue from a or after surgery.
Treatment for ER-positive breast cancer
If your breast cancer is ER-positive, you may be offered hormone therapy.
A number of hormone therapies work in different ways to block the effect of oestrogen or reduce the amount of oestrogen in the body.
It may be given to:
- Reduce the risk of breast cancer coming back after surgery
- Reduce the size of the cancer or slow down its growth
- Treat breast cancer that has come back or spread
3. Progesterone and breast cancer
Progesterone is another hormone that plays a role in the female reproductive system.
Sometimes breast cancer cells contain progesterone receptors. This is called progesterone receptor positive or PR-positive breast cancer.
Invasive breast cancers should also be tested for progesterone receptors.
Treatment for PR-positive breast cancer
Most PR-positive breast cancers are also ER-positive, and you may be offered hormone therapy.
The benefits of hormone therapy are less clear for people whose breast cancer is only PR-positive. Very few breast cancers fall into this category, but if this is the case your specialist will discuss with you whether hormone therapy is suitable.
4. When cancer has no hormone receptors
If your cancer has no hormone receptors, it is hormone receptor negative.
If this is the case, hormone therapy will not be of any benefit and your specialist will discuss with you which other treatments are suitable.
