What is breast cancer?

What is breast cancer?

Breast cancer is the third most common cancer diagnosed in New Zealanders. In 2015 there were 3,315 new registrations of breast cancer—3,292 of these were in women and 23 in men.

Women and men both have breast tissue. In women, breasts are made up of milk glands, connective tissue and fat. The milk glands consist of milk sacs (lobules) where milk is made, and ducts that take the milk to the nipple.

breast malebreast woman

During puberty males produce increased amounts of the male hormone testosterone, which suppresses the development of lobules in their breast tissue.

Breast tissue is made up of millions of cells that are like tiny ‘building blocks’. Breast cancer is a disease of these breast tissue cells. Normally, cells reproduce and grow in an orderly way. However, sometimes an abnormal cell develops that can continue to reproduce and grow into a tumour. Tumours can be benign (not cancerous) or malignant (cancerous).

A malignant tumour is made up of cancer cells. When it first develops, the malignant tumour may be confined to its original (primary) site. If these cells are not treated they may spread beyond their normal boundaries and into surrounding tissues (invasive cancer).

Breast cancer that comes back in the same breast is called a local recurrence. When it spreads to areas around the breast, such as the skin, the muscles on the chest wall, the lymph nodes under the breastbone (sternum), between the ribs, or the nodes above the collarbone (clavicle), it is called regional recurrence. Both of these types of recurrence will need further treatment, but they are not secondary breast cancer.

For more information about primary breast cancer, see our booklet Breast Cancer/Te Matepukupuku o ngā Ū.

Leave us a message