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Breast cancer

Breast cancer is an area of tissue that has an abnormal and uncontrolled growth of cells (tumour). It can either be malignant (cancerous) or benign (not cancerous). Nine out of 10 breast lumps are benign.

About breast cancer

Each year, around 44,000 women are diagnosed with breast cancer in the UK, making it the most common cancer in women. Breast cancer can also occur in men, but this is rare.

One in nine women develops breast cancer at some time in their life. Breast cancer is most common women over 50.

The breasts

Your breasts are made up of fat, connective tissue and gland tissue divided into lobes. The lobes are connected to your nipple by ducts.

Breast cancer usually starts in the cells lining the ends of the lobes and in the ducts themselves.

Cancerous tumours can grow through your breast, spread to other parts of your body and invade surrounding tissue. For more information, see Related topics.

Types of breast cancer

Non-invasive breast cancers

Non-invasive breast cancers are cancers that remain within the ducts or lobes of the breast and do not spread to surrounding tissue or to other parts of the body.

The most common type of non-invasive breast cancer is ductal carcinoma in situ (DCIS). The cancer cells are only found inside the milk ducts and haven't spread through the walls of the ducts into the breast tissue. In some cases, DCIS may then develop into an invasive form of breast cancer.

Invasive breast cancers

Invasive breast cancers are cancers that have started to spread from the ducts or lobes of the breast into surrounding tissue.

The most common type of invasive breast cancer is called invasive ductal carcinoma (IDC), where the cancer cells are in the ducts and the breast tissue. Around three in four people diagnosed with breast cancer have this type.

About one in ten women get invasive lobular carcinoma (ILC), which starts growing in the lobes, but can spread to other parts of the breast.

Both IDC and ILC can spread to other parts of the body.


Some women with breast cancer don't notice any changes in their breasts. Other women notice a lump or a change in the overlying skin or nipple. Although not necessarily a result of breast cancer, if you have these symptoms or notice any changes in your breasts, you should visit your GP. For more information on how to be aware of changes in your breasts, see Related topics.


The cause of breast cancer isn't yet fully understood. But certain factors make breast cancer more likely. You are more likely to develop breast cancer if you:

  • are over 50 (about eight in 10 women diagnosed with breast cancer are over 50)
  • have had cancer in one breast already
  • started your periods early or your menopause late
  • have been exposed to radiation
  • had a first pregnancy after the age of 30, or don't have children
  • have a diet high in fat
  • drink excess alcohol
  • are overweight and have been through the menopause
  • have family history of breast cancer through an inherited faulty gene (however, breast cancer is common, so it may be in your family by chance)

If you take the contraceptive pill or hormone replacement therapy (HRT), you have a slightly higher risk of breast cancer.


Your GP will ask you about your medical history and about any of the risk factors above. He or she will also examine your breasts.

Your GP may refer you to have further tests including:

  • an ultrasound scan
  • a mammogram, which is an X-ray of your breast
  • a biopsy, for which your doctor will surgically remove a suspicious lump or collect a small sample of tissue with a needle
  • a needle aspiration, for which your doctor will use a fine needle to collect a sample of cells from your breast
  • CT (computerised axial tomography) and MRI (magnetic resonance imaging) scans - these can help your doctor tell how far the cancer has spread (if at all)

For more information, see Related topics.


Your treatment for breast cancer will depend on a number of factors such as your age and whether the cancer has spread and if so, how far. Your doctor will advise you on which treatment is best for you. For more information, see Related topics.


The first step in treating breast cancer is usually to surgically remove the lump.

You can either have a lumpectomy (also called a wide local excision) where the lump is removed, usually with some healthy tissue, or a mastectomy. A mastectomy removes the whole of your affected breast. With both of these procedures, some lymph nodes will be removed from your armpit. You may have other treatments after surgery aiming to reduce the chance of the cancer coming back, or spreading to other organs.

You should be able to choose whether you would like a breast reconstruction, an operation to make a new breast shape, after a mastectomy.


Radiotherapy uses radiation to destroy cancer cells.


Chemotherapy is a treatment to destroy cancer cells with medicines. You may also receive chemotherapy to shrink a tumour in preparation for surgery.

Hormone therapy

Hormonal medicines can block the action of oestrogen, a hormone that can encourage some breast cancers to grow. Hormonal medicines, such as tamoxifen (eg Nolvadex) treat tumours or make them less likely to re-occur. Aromatase inhibitors such as anastrozole (Arimidex) and letrozole (Femara) are another type of hormonal treatment. They stop the body making oestrogen. Aromatase inhibitors are only given to women who have been through the menopause.

You may need to take hormonal treatments for a number of years following your initial treatment.

Biological therapies (monoclonal antibodies)

Antibodies are proteins produced by the immune system that usually fight against bacteria and viruses. Monoclonal antibodies are made in a laboratory and designed to seek out particular cells.

One such medicine, trastuzumab (Herceptin), targets breast cancer cells that have a protein called HER2 on their surface. Trastuzumab is used in women who have a particular genetic flaw that produces the protein HER2.


The NHS Breast Screening Programme invites all women between the ages of 50 and 70 for breast screening every three years. Breast screening, and being breast aware by examining your own breasts for any changes, can help you find small changes in your breasts before there are any other signs. Contact your GP if you notice any differences.

Being active, breastfeeding, and eating a healthy diet may also protect against breast cancer.

Help and support

Being diagnosed with cancer can be distressing for you and your family. An important part of cancer treatment is having support to deal with the emotional aspects as well as the physical symptoms. Specialist cancer doctors and nurses are experts in providing the support you need, and may also visit you at home.

Further information

Breast Cancer Care

Macmillan Cancer Support

Cancer Research UK


  • Breast cancer. Cancer Research UK. www.cancerhelp.org.uk, accessed 12 December 2007
  • Cassidy J, Bissett D, Spence RAJ. Oxford Handbook of Oncology. Oxford: Oxford University Press, 2002:295-322
  • Breast screening the facts. Department of Health. www.dh.gov.uk, accessed 12 December 2007
  • Women with breast cancer in the family. National Institute of Clinical Excellence (NICE), Information about NICE clinical guideline 41, October 2006. www.nice.org.uk
  • Target Breast Cancer. The Association of the British Pharmaceutical Industry (ABPI). www.abpi.org.uk
  • British National Formulary 54, Section, September 2007. Breast cancer. www.bnf.org
  • British National Formulary, 54, Section, September 2007, Herceptin. www.bnf.org

Related topics

  • Breast awareness and screening
  • Breast lumps
  • Cancer - a general overview
  • Chemotherapy
  • CT scan
  • Mastectomy
  • MRI scan
  • Radiotherapy