What is Breast Cancer?

Unfortunately, if left untreated, the primary tumour can spread via the lymph nodes or blood vessels to other parts of the body including the liver, lungs and bones. The spread of cancer can create more tumours around the body, which is called metastasis.

Breast cancer affects both women and men, but is the most common cancer affecting Australian women. In 2021, breast cancer was the most commonly diagnosed cancer in Australia.

Some breast cancers, known as ‘pre-invasive’ or ‘carcinoma in situ’ breast cancers, appear inside the milk ducts or milk-producing lobules of the breast. Other ‘invasive’ breast cancers grow within normal breast tissue and may spread to elsewhere in the body. There are various types of breast cancer, including

• Paget’s disease
• Inflammatory breast cancer
• Ductal carcinoma
• Lobular carcinoma
• Hormone receptor positive breast cancer
• HER-2 positive breast cancer
• Triple negative breast cancer (which tests negative for oestrogen, progesterone and HER-2).

Breast cancer is most commonly divided into stages based on the tumour size and how much it has spread around the body. Breast cancer has five main stages, from 0 to 5 and this is determined based on a number of factors including:

• Size of the tumour
• If the cancer is invasive or non invasive
• If the cancer has spread to nearby tissue or organs
• If lymph nodes have been affected.