  Hormones and cancer  High levels of hormones can affect our
risk of 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?  Reproduct