Breast cancer can be non-invasive or invasive.

Non-invasive breast conditions

Non-invasive breast cancer describes the presence of abnormal cells that have not invaded the surrounding normal breast tissue. Types of non-invasive breast cancer include:^1,3

• Ductal carcinoma in situ (DCIS)
• Abnormal cells are found within the milk ducts of the breast
• Treatment options include surgery and radiation therapy – your doctor may perform tests to determine which treatments are appropriate for your DCIS
• Lobular carcinoma in situ (LCIS)

Invasive breast cancer

Invasive breast cancer means that the cancer cells have spread outside the ducts or lobules of the breast to nearby breast tissue. Types of invasive breast cancer include:^1,3

• Early breast cancer
  • Refers to cancer that is contained within the breast and may have spread to nearby lymph nodes in the breast or armpit, but not anywhere else in the body
  • The two main types are invasive ductal carcinoma (IDC) and invasive lobular carcinoma (ILC)
• Locally advanced breast cancer
  • Describes breast cancer that has spread to other nearby areas, such as the chest wall (including the skin and muscles of the chest) and lymph nodes
• Secondary (metastatic or advanced) breast cancer
  • Describes breast cancer that has spread to other parts of the body, such as the bones, liver, or lungs

• Stages (0 to 4) – this system assesses tumour size, whether the cancer has spread into the lymph nodes, and whether it has spread into other parts of the body (metastasised)^1,3
• Grade (low, intermediate, or high) – this describes the activity and growth of the cancer cells³
• Hormone receptor (HR) and human epidermal growth factor receptor 2 (HER2) status – whether the cancer cells have extra HR or HER² or not³

The body naturally produces the hormones oestrogen and progesterone. Normal breast cells have oestrogen receptors (ER) and progesterone receptors (PR). Breast cancer is categorised as ER+ or PR+ when there are too many of the respective receptors. Similarly, tumours that have high levels of human epidermal growth factor receptor 2 (HER2) proteins on their surface are categorised as HER2+. Triple negative breast cancers are both hormone receptor negative (ER- and PR-) as well as HER2 negative (HER2-).³

While the exact cause of breast cancer is unclear, a number of factors can increase your risk of developing breast cancer. Some risk factors that cannot be changed include:³

• Increasing age
• Family history of breast cancer
• Genetic mutations
• Exposure to female hormones
• Starting your period early (before the age of 12)
• A previous diagnosis of breast cancer
• History of certain non-cancerous breast conditions
• Dense breast tissue (as seen on a mammogram)

In addition, lifestyle factors such as being overweight, not enough physical activity, and drinking alcohol can increase the risk of breast cancer.³

Approximately 5–10% of breast cancer cases are due to an inherited genetic mutation. In addition, a strong family history (e.g., several close relatives on the same side of the family) of breast or ovarian cancer may increase your risk of breast cancer.³

Being female is the biggest risk factor for breast cancer, but it can also occur in men (99% of cases are diagnosed in women).³ Lifestyle factors such as being overweight, not enough physical activity, and drinking alcohol can also increase the risk of breast cancer in men.³

Breast changes may indicate early signs of breast cancer, and these can vary from person to person. For many people, there may be no obvious signs or symptoms. Breast changes that can be associated with breast cancer include:^1,3

• A lump or mass in the breast, especially if in just one breast
• Change in size or shape of the breast
• Swelling or pain in the breast
• Nipple changes (e.g., inversion) or discharge
• Skin changes (e.g., dimpling, redness, scaliness, itchiness)
• A lump, swelling, or pain in the underarm

Other, benign conditions can also cause breast changes, but it’s important to be assessed by a doctor if you notice any of these symptoms.

If you think you may be experiencing breast cancer symptoms or have any questions about breast cancer or your risk for developing it, we recommend speaking to your doctor.

Mammograms can be used to detect breast cancer early for women who have no symptoms of breast cancer and can find changes that are too small to be felt during a physical examination.⁴ If you have symptoms such as a lump but your mammogram is normal, or if you are worried for any other reason, we recommend that you speak with your doctor.

If breast changes are detected on mammography, other tests that may be used to diagnose breast cancer include:³

• Ultrasound – creates images of breast tissue using sound waves
• Magnetic resonance imaging (MRI) scan – creates computerised images of breast tissue using a large magnet and radio waves
• Biopsy – removes a small sample of breast tissue or cells from the lump or area of concern, which is examined under a microscope for the presence of cancer cells

If these tests detect breast cancer, you may undergo further testing to see if the cancer has spread to other parts of your body. These tests may include blood tests, computerised tomography (CT) scans, bone scans, and positron emission tomography (PET) scans.³

If you find a lump in your breast, it doesn’t automatically mean that it’s cancer – there are a number of possible causes of non-cancerous breast lumps.¹ When detected and treated early, breast cancer has a high survival rate.^1,3

Although there is no proven method for preventing breast cancer, reducing alcohol consumption and maintaining a healthy weight may help to reduce the risk of breast cancer.³

National screening programs

Cancer screening programs aim to pick up cancers in healthy individuals who do not have symptoms. Screening mammography, which is a low dose X-ray taken of the breast, is used for the early detection of breast cancer. The government’s national screening program, BreastScreen Australia, targets women aged 50 to 74 years because 75% percent of all breast cancers occur in women over the age of 50 years.^1,4

• Women aged 50 to 74 years are encouraged to have a free mammogram every two years
• Women aged 40 to 49 years with no symptoms are also eligible to receive free screening mammograms if desired
• Women aged 75 years and over with no symptoms are also eligible for free screening mammograms but should first discuss options with their GP

Treatment for breast cancer usually includes using surgery to remove some (lumpectomy) or all breast tissue (mastectomy) and one or more lymph nodes. The type of surgery recommended will depend on your diagnosis and other factors.³

Radiation therapy uses radiation (usually x-ray beams) to destroy cancer cells in the affected area. There are different modern techniques that allow clinicians to deliver a precisely targeted dose just to the areas of breast tissue and lymph nodes that require treatment.³

Some of the modern techniques used for breast cancer radiation therapy include:

• Deep inspiration breath hold (DIBH) – uses deep breaths to help target the treatment area and protect the heart and lung during delivery of radiation therapy⁵
• Hypofractionation – helps to reduce overall treatment time for the patient by delivering a slightly higher radiation therapy dose during each session⁶
• Tattoo-free treatment – uses surface-guided radiation therapy (SGRT) to precisely position the patient so that treatment can be accurately targeted at each session without the need for tattoos or other permanent markers on the skin and allowing for shorter daily treatment set-up times⁷
• Image-guided radiation therapy (IGRT) – uses repeated imaging to track and target the treatment site with precision, even as it changes size and shape, allowing dose or position to be adjusted during treatment to protect unaffected tissue⁸
• Volumetric modulated arc therapy (VMAT) – uses a moving machine to shape the arc of radiation to the target area⁸

Chemotherapy uses medication to kill cancer cells or reduce their growth and spread. The type of chemotherapy drugs recommended will depend on your breast cancer diagnosis and other factors.³

Hormone therapy may be used for certain types of breast cancer to help reduce the risk of the condition from getting worse or coming back. The type of hormone therapy recommended is based on age and diagnosis.³

Targeted therapy uses medications that are designed to attack specific features of cancer cells to stop these cells from growing and spreading. Targeted therapy may only be suitable for certain types of breast cancer.³

Your immune system is designed to protect your body from threats such as infections, toxins and abnormal cell development (cancer).^9,10 While your immune system can help to prevent or slow cancer growth, cancer cells have ways to avoid detection and destruction by immune cells.⁹

Immunotherapy medicines boost or improve how your own body’s immune system works to fight cancer.⁹ Immunotherapy medicines work in different ways and include: 

• Checkpoint inhibitors: These medicines take the ‘brakes’ off the immune system, which helps it to then recognise and attack cancer cells.^9,10
• Chimeric antigen receptor (CAR) T-cell therapy: T-cells from a patient’s blood are mixed with a special virus that makes the T-cells learn how to attach to tumour cells.  These cells are then given back to the patient so they can find, attach to, and kill the cancer.^9,10
• Cytokines: Cytokines are small proteins that carry messages between cells. They are used to stimulate the immune cells to attack cancer.¹¹
• Immunomodulators: Boost parts of the immune system to help treat certain types of cancer.⁹
• Cancer vaccines: Vaccines are being researched and developed with the aim of preventing or treating cancer through an immune response.⁹