We do not know what causes breast cancer however risks associated with breast cancer are:

Age - about 80 per cent of women who are diagnosed with breast cancer are over 50 and half of those are over 60

Starting your periods early in life or having a late menopause

A family history of breast cancer

Being overweight after the menopause

Poor diet

Alcohol - the more a woman drinks each day the greater the risk

Hormone replacement therapy (HRT) with the risk increasing the longer it's taken, but within five years of stopping HRT the risk returns to normal

This risk is reduced by having children at a younger age. The more children a woman has also lowers the risk.

Breastfeeding also reduces the risk.

A more active lifestyle reduces breast cancer risk

People with a strong family history of breast cancer (those with several close relatives who've had it, or a mother or sister who developed the disease before the age of 50 or before the menopause) may be offered an assessment of their risk and genetic screening using a blood test, if appropriate.

The contraceptive pill - although the level of risk returns to normal after a woman stops taking it