Breast cancer
Breast cancer is the most common cancer in the UK, affecting around 1 in 7 women during their lifetime. It can also occur in men, though this is rare. Most breast cancers are diagnosed in women over 50, but it can occur at any age.
The first noticeable symptom is usually a lump or area of thickened tissue in the breast, though not all lumps are cancerous. Other signs may include a change in the size or shape of the breast, dimpling of the skin, nipple discharge or a rash around the nipple.
The NHS Breast Screening Programme invites women aged 50 to 71 for mammograms every three years. Blood tests such as CA 15-3 are used primarily to monitor treatment response in women already diagnosed with breast cancer, rather than as a screening tool.
Polygenic risk scores assess the combined effect of multiple genetic variants on breast cancer risk, offering an additional layer of personalised risk assessment beyond family history alone.
Causes of Breast cancer
Breast cancer develops when cells in the breast tissue grow and divide in an uncontrolled way. The precise trigger for this in any individual is usually unknown, but several risk factors have been identified:
- Age is the most significant risk factor. The majority of breast cancers are diagnosed in women over 50
- Family history and genetics account for around 5 to 10% of cases. Inherited mutations in the BRCA1 and BRCA2 genes significantly increase lifetime risk. Polygenic risk scores can assess the cumulative effect of many common genetic variants
- Hormonal factors, including starting periods early, having a late menopause, not having children or having a first child later in life, and using hormone replacement therapy (HRT), all modestly increase risk due to prolonged oestrogen exposure
- Lifestyle factors including being overweight (particularly after the menopause), physical inactivity, drinking alcohol and smoking are associated with increased risk
- Previous breast conditions, including certain types of non-cancerous breast disease and previous radiotherapy to the chest area
Having one or more risk factors does not mean breast cancer will develop. Equally, breast cancer can occur in women with no identifiable risk factors.
Tests that can help check this condition
Learn more on the official NHS page .
