1. How hormones can affect breast cancer
2. Oestrogen receptor positive (ER+) breast cancer
3. Progesterone and breast cancer
4. When cancer has no hormone receptors

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 oestrogen receptors and progesterone receptors.  

2. Oestrogen receptor positive (ER+) 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, often shortened to ER+.

When oestrogen receptors are found in breast cancer cells, this can help the breast cancer to grow. 

All invasive breast cancers are tested for oestrogen receptors using tissue from a biopsy or after surgery. Invasive breast cancer is cancer that has the potential to spread.

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, often shortened to PR+.

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. 

Last reviewed: March 2021
Next planned review begins 2023

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