Hormones and cancer
Our bodies are full of hormones that tell our cells what to do. At high levels, these naturally-occurring hormones can increase our risk of some cancers by encouraging cells to multiply more than they usually would.
This section will discuss the links between hormones and cancer. You can find out about different sources of hormones and whether they affect your risk of cancer. These include:
What is a hormone?
Hormones are naturally occurring substances that are produced in specific parts of our bodies and act as chemical messengers. They travel through the blood to control the functions of other tissues and organs. Because they have such important roles, the levels of hormones in our bodies are carefully controlled.
Part of the role of hormones is to help control when and how often cells multiply. Changes in hormone levels can interfere with this process. And that can lead to cancer.
What affects our hormone levels?
A woman's hormone levels change throughout her life, for example as she goes through her menstrual cycle or if she has children. These 'reproductive factors' are linked to risks of hormone-related cancers, such as breast and womb cancer. They include:
- being pregnant
- having children
- the age at which a woman has a first child
- whether she breastfeeds and for how long
- the age at which she starts menstruating
- the age at which she goes through menopause
Reproductive factors generally aren't something we can control. But this doesn't mean that there is nothing you can do to reduce the risk of hormone-related cancers.
Maintaining a healthy bodyweight can help to keep hormone levels under control. This is especially important in women after the menopause, whose ovaries have stopped making hormones. When this happens, fat cells become the main hormone source.
People who are overweight or obese have much higher levels of hormones such as oestrogen, insulin and insulin-like growth factors (IGFs). This may explain why they have higher risks of breast, bowel and womb cancers.
There is also some evidence that drinking too much alcohol and not getting enough physical activity could increase a woman's levels of oestrogen. This may be why these things also increase the risk of breast cancer.
Your body makes its own hormones, but some medicines can also change your hormone levels. These include:
- hormone replacement therapy (HRT)
- the contraceptive Pill
- some cancer drugs, such as tamoxifen, work by altering hormone levels. You can read more about cancer treatments on CancerHelp.
Question about cancer? Contact our information nurse team