Young people, breasts and breast cancer

Your breasts will usually start to develop around age 9 to 11, but it’s quite normal for them to start earlier or later than this. They come in all different sizes and shapes and are usually fully developed by the age of 17.

Everyone’s breasts develop at different rates, so don’t worry if your friend's breasts are bigger or smaller than yours. You breasts will also change in size and appearance at different times of your life – for example, when you have your period, if you have a baby, and when you get older and your periods stop.

Young people and breast cancer

Developing breast cancer when you are a teenager is very rare. It is also uncommon in women in their 20s and 30s. The vast majority of breast cancers are diagnosed in women over the age of 50.

It can be normal for lumps to be felt when a girl's breasts are developing and these often disappear on their own. Sometimes these lumps can be benign (non-cancerous) conditions which can also settle down on their own.

If the lump causes you any discomfort or appears to get bigger in size you may need to talk to someone such as your GP. You may also want to talk to someone in your family or school nurse who is able to offer practical help and support.