What is breast cancer?
Breast cancer starts in the ducts or lobules of the breast. Cells lining the ducts or lobules can grow out of control and develop into cancer.
Breast cancer types
Some breast cancers are found when they are still confined to the ducts or lobules of the breast. This is called pre-invasive breast cancer. The most common types are ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS).
Most breast cancers are found when they are invasive. This means the cancer has spread outside the ducts or lobules of the breast into surrounding tissue.
There are several categories of invasive breast cancer.
Early breast cancer: contained in the breast but may have spread to one or more lymph nodes in the armpit.
Locally advanced breast cancer: may have spread to places near the breast, such as the chest (including the skin, muscles or bones of the chest), but the cancer isn’t found in other areas of the body.
Metastatic breast cancer: the cancer cells spread from the breast to other areas of the body, such as the bones, liver or the lungs. It may also be called advanced breast cancer.
How common is breast cancer?
Breast cancer is the most common invasive cancer in women in Australia. One in eight women will be diagnosed with breast cancer by the age of 85. Over 15,050 women are diagnosed with breast cancer each year.
Breast cancer can occur at any age. It is more common in women aged over 60 but nearly one-quarter of women are younger than 50.
Men can also develop breast cancer, although this is rare. More than 100 men are diagnosed each year in Australia.
Breast cancer causes
The exact cause of breast cancer is unknown, but there are factors increase the risk to developing this disease:
- Increasing age
- Family history - having several close relatives, like a mother, sister or daughter, diagnosed with breast cancer from either the mother’s or father’s side of the family
- Inheritance of mutations in the genes BRCA2, BRCA1 and CHEK2
- Exposure to female hormones (natural and administered)
- If you have had breast cancer before If you have had certain breast conditions such as atypical ductal hyperplasia, ductal carcinoma in situ or lobular carcinoma in situ
- Obesity (poor diet and inadequate exercise) and
- Excess alcohol consumption
- Having some of these risk factors does not mean that you will develop breast cancer
Most women with breast cancer have no known risk factors, aside from getting older.
Breast cancer symptoms and diagnosis
Women of all ages should be familiar with the normal look and feel of their breasts. If you notice any of the following changes please see your doctor immediately.
- new lumps or thickening in the breast or under the arm
- nipple sores
- nipple discharge or turning in
- skin of the breast dimpling
- rash or red swollen breasts
Pain is rare.
Diagnosis is usually by imaging e.g. mammogram, then biopsy by needling or removing the lump.
Breast cancer screening
Free Mammographic screening every two years is recommended for women aged 50-74 years, though it is available free to women from 40 years of age. Women can contact their local BreastScreen Australia service by phoning 13 20 50. Younger women in high risk groups may be screened by Magnetic Resonance Imaging (MRI).
Breast cancer treatment
Treatment depends on the extent of the cancer.
For localised breast cancer, the most extensive surgical option is to remove the breast and lymph nodes under the arm. However, removing the lump and just a section of the breast, followed by radiotherapy, results in the same rate of survival. If the first draining lymph node can be identified using dye or a nuclear medicine scan, it can be sampled and if it is negative, further surgery avoided.
For tumours at greater risk of recurrence i.e. bigger, more aggressive cancers, or cancers that have spread to the lymph nodes, additional treatment (adjuvant therapy) can be given after surgery. This can include hormone therapy of aromatase inhibitors or tamoxifen for women whose tumours have hormone receptors on their surfaces, and chemotherapy and targeted therapies such as trastuzumab for those 25% of tumours that are HER2 positive (i.e. have the target for trastuzumab on their surfaces).
Patients presenting with locally extensive cancer will have chemotherapy and radiotherapy initially to see if it will shrink the cancer to make it operable.
If breast cancer returns after initial treatment, local disease may be treated with surgery, while more widespread disease will be treated with combinations of similar drugs to those used in adjuvant treatment. Common chemotherapy drugs include anthracyclines and taxanes.
Patients with bone disease can receive bisphosphonates such as zoledronate to slow the erosion of bones, and receive local radiotherapy for pain.
Breast cancer prognosis
An individual’s prognosis depends on the type and stage of cancer as well as their age and general health at the time of diagnosis. If the cancer is limited to the breast, 96% of patients will be alive five years after diagnosis; this figure excludes those who die from other diseases. If the cancer has spread to the regional lymph nodes five year relative survival drops to 80%. In Australia, the overall five year survival rate for breast cancer in females is 89%.