Risks and causes of breast cancer
Around one in eight women in the UK develop breast cancer during their life, making it the most common cancer in women.
Around 49,560 women and 400 men are diagnosed with breast cancer in the UK each year, according to Cancer Research UK.
It isn't always possible to know exactly what causes a person's breast cancer.
Something which increases the chances of developing a condition is called a risk factor. With breast cancer, some risk factors cannot be influenced, such as those cancers that are genetically inherited. However, other risks may be able to be reduced or modified.
Having a risk factor or several risk factors doesn't mean a person will definitely develop breast cancer, but the chances may be higher.
Here are some breast cancer risk factors:
Age and development
The chances of developing breast cancer increases with age, which is why the NHS breast screening programme invites women aged 47 - 73 years old for screening. Some women with a family history of breast cancer may be screened sooner.
Eight out of 10 women who are diagnosed with breast cancer are over 50. However, the disease can still affect younger women and men.
Life's milestones also appear to have an effect. Starting periods early seems to increase the risk, as does late menopause.
Having children younger and breastfeeding reduces the risk of breast cancer.
Most cases of breast cancer are not inherited, or run in families. However, having a close relative, such as a sister or mother, who has had breast cancer or ovarian cancer may increase the risk. Having a male blood relative with breast cancer will also increase a woman's risk of the disease.
Genes called BRCA1, BRCA2 and TP53 are linked to breast cancer.
Weight, shape and exercise
Being overweight or obese and having a high body mass index (BMI) causes a moderate increase in developing breast cancer after menopause. Being tall is also thought to increase a woman's risk of breast cancer after the menopause.
According to the NHS, it has been suggested that regular exercise can reduce the risk of breast cancer by as much as a third. Currently it’s recommended to do at least 150 minutes of moderate physical activity a week.
Alcohol diet and smoking
Drinking too much alcohol appears to increase a woman's risk of developing breast cancer. According to Cancer Research UK the risk increases with every extra unit of alcohol consumed per day.
Having an unhealthy diet, including eating too much saturated fat, may increase the chances of developing cancers. A healthy balanced diet, lower in fat and with at least 5-a-day portions of fruit and vegetables is recommended.
Smoking and secondhand smoke has been linked to cancers, such as lung cancer, but there's also evidence it may increase the risk of breast cancer too.