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.

Useful resources

This Teachers' Maternity Leave Scheme has been updated to reflect the rules concerning...
EA is committed to ensuring that all individuals are treated fairly and with dignity and...
Cancer Focus NI can provide a wide range of presentations to meet the needs of your...
Sometimes when faced with an unplanned or crisis pregnancy it is difficult to discuss it...
This programme is a six week training programme for groups of adults and focuses on...
The Menopause Project is an education and research project between Informing Choices NI...
We all have good and bad days but what and when we eat can influence our mood, energy,...
There are a number of health campaigns throughout the year to raise awareness of...
Around one in five women will experience a mental health issue during pregnancy or within...
Cancer Focus NI, Keeping Well vans are mobile drop-in units which bring health checks,...
This includes: Raising awareness of depression and Aware NI services at a wide range of...
We are delighted to provide this FREE digital toolkit. Designed in partnership with the...
Affected by breast cancer? Join this group to share experiences and ask questions to...
Support for breast cancer
Guided meditations
Learn to manage negative thoughts and look at problems differently
Food diary, exercise tracker and diet coach
Support hub for mothers
Track your treatment and wellbeing
Pregnancy and guidance for after birth
Active 10 is a free and easy to use walking app that tracks your walking and shows you...
It’s an easy to follow programme known the world over, and perfect for those new to...
Guided meditations
Handle stress and anxiety on the go
This short test will help you understand how heavy your periods are, and point you in the right direction for treatment options.
Your Mind Plan offers practical ideas and advice to help you boost and maintain your mental wellbeing. Answer the quick 5-question quiz and the Every Mind Matters widget will give you 5 tailored actions to help you feel more in control, improve your sleep, deal with stress and anxiety, and boost your mood – as well as the option to easily swap any actions and to save the whole plan via email.

Articles & Videos

Helplines & Web Chats

Informing Choices NI - Helpline
Royal Osteoporosis Society - Helpline
Macmillan - Forum
Macmillan - Ask an expert
Women's Aid - Forum
Association for Post-Natal Illness Helpline
Women's Aid - Domestic abuse helpline