Causes & Symptoms

Macmillan Cancer Support

Doctors do not know the exact causes of breast cancer. But there are risk factors that can increase your chance of developing it.

Having one or more risk factors does not mean you will get breast cancer. Also, having no risk factors does not mean you will not develop it.

Breast cancer is likely to be caused by a combination of different risk factors, rather than just one.

It is important to see your GP if you have any of the following symptoms or notice anything that is unusual for you.

Possible signs and symptoms of breast cancer can include:

  • a lump in the breast
  • thickening of the skin or tissue of the breast, or dimpling of the skin of the breast
  • a lump or swelling in either armpit
  • a change in the shape or size of the breast, such as swelling in all or part of the breast
  • a nipple turning in (inverted nipple)
  • a rash (like eczema) on the nipple
  • discharge or bleeding from the nipple
  • pain or discomfort in the breast that does not go away, but this is rare.

A lump in the breast is the most common symptom of breast cancer, but most breast lumps are not cancer. They are usually lumps either filled with fluid (a cyst) or made up of fibrous and glandular tissue (fibroadenoma).

But it is very important to get any of these symptoms or anything else that is unusual for you checked by your GP.

The earlier you get a diagnosis and start treatment, the more successful treatment is likely to be..

During pregnancy, a woman’s breast tissue changes. Sometimes a lump or another breast cancer symptom could be confused with this. If you are pregnant and have any of these symptoms, it is important to see your doctor. Your symptoms should be checked in the same way as in women who are not pregnant.

We understand that showing any symptoms of what could be cancer is worrying. The most important thing is to speak to your GP as soon as possible.

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