Breast cancer

Breast cancer is when cells in your breast change and grow in an abnormal way. A group of these cancer cells can form a tumour.

Breast cancer is a common cancer in Ireland. Almost 3,600 women and approximately 30 men are diagnosed with breast cancer each year.*

Your breasts are made up of different types of tissue including fat, connective tissue and gland tissue. The gland tissue is divided into milk lobes and milk ducts. During and after pregnancy, milk is made and stored by the lobes and carried to the nipple by the ducts.

Your breasts are rarely the same size as each other. They may feel different at different times of the menstrual cycle, sometimes becoming lumpy just before your period. Under your skin, a ‘tail’ of breast tissue extends into your armpit (axilla).

The armpits also contain a collection of lymph nodes (glands) that make up part of the lymphatic system.

Having a risk factor doesn’t mean you will get cancer. Sometimes people with no risk factors get the disease.

Read more about risk factors and reducing your risk of breast cancer.

BreastCheck is the name of the national breast screening programme. It offers free breast screening to women, transgender, intersex and non-binary people age 50 to 69. You must be living in Ireland and have a PPS number.

For more information contact BreastCheck directly at Freephone 1800 45 45 55 or visit the BreastCheck website.

Medical content updated from our 'Understanding breast cancer' booklet (2024), reviewed by Prof Janice Walshe, Consultant Medical Oncologist and Clinical Professor, Prof Malcolm R. Kell, Consultant Surgeon and Clinical Professor, Dr Orla McCardle, Consultant Radiation Oncologist, Niamh Byrne, Breast Care Nurse and Teraze Toby, Daffodil Centre Nurse.