Breast cancer

Last Review Date: August 1, 2018

What is it?

Breast cancers are tumours that arise from the uncontrolled growth of cells in the breast. They occur in the ducts that transport milk to the nipple during breast feeding (lactation) or in the lobules, the glands that produce milk.

Each breast cancer has its own characteristics. Some are slow-growing; others can be aggressive. Some cancers are sensitive to the hormones oestrogen and progesterone, while others can over-express certain proteins. The cancer's characteristics can affect treatment choices and the potential for the cancer to recur.

In 2017, it is estimated that the risk of an individual being diagnosed with breast cancer by their 85th birthday will be 1 in 14 (1 in 715 males and 1 in 8 females). The Australian Institute of Health and Welfare estimates that 18,235 new cases of breast cancer (148 males and 18,087 females) will be diagnosed in 2018. The estimated number of death from breast cancer in 2018 is 3,157 (28 males and 3,128 females). The rest of this article will focus on breast cancer in women. It is recommended that men who have been diagnosed with breast cancer speak to their healthcare provider for information specific to them.

Breast cancer can develop at any age, but the risk of developing it increases as women get older. The majority of cases develop for reasons we do not yet understand. Some of those at higher risk of developing breast cancer include women:

  • With close relatives (mother, sister, aunt) who have had the disease
  • Who have had a cancer in the other breast
  • Who have not had children
  • Who had their first child after the age of 30
  • With an inherited mutation in breast cancer genes, usually either BRCA1 or BRCA2. About 5% to 10% of breast cancers are related to these mutations. BRCA1 and BRCA2 are two tumour suppressor genes that help prevent cancer by producing proteins that suppress abnormal cell growth. Mutations in these genes can affect their normal function, potentially allowing uncontrolled cell growth and increasing the risk of cancer. Women with inherited BRCA1 or BRCA2 mutations have up to an 85% lifetime risk of developing breast cancer.

A healthy lifestyle that includes regular exercise, maintaining a healthy body weight, and avoiding alcohol may help to minimise the risk of developing breast cancer. Research studies continue to identify factors that are associated with an increased or decreased risk of developing the disease, but there is no single set of actions that will cause or prevent breast cancer. Family history and exposure to oestrogen are among the most important factors in breast cancer risk. Women should work with their doctor to determine their personal risk factors and how to address them.

For those women who have a gene mutation such as BRCA1 and BRCA2 that is frequently associated with breast cancer, prophylactic mastectomy is an option. Women electing this option choose to have both breasts removed before developing cancer rather than run the high risk of developing the disease later in their lifetime. Studies have shown that such surgery can reduce the risk of developing breast cancer by up to 97%. Other women elect to have a prophylactic mastectomy on their cancer-free breast after developing cancer in the other breast. A doctor can help advise and work with a woman who is considering prophylactic mastectomy.


It is important to remember that most lumps found in the breast are not cancerous but are benign and that the signs and symptoms associated with breast cancer may be due to other causes. Some signs and symptoms include:

  • Lump in the breast
  • Breast skin dimpling, reddening, or thickening
  • Nipple retraction
  • Breast swelling or pain
  • Nipple pain and/or discharge
  • Swelling or lumps in underarm lymph node
  • Pigmented, peeling, scaling or flaking skin in the area around the nipple
  • Changes in size, shape or appearance of the breast

A rare form of breast cancer, inflammatory breast cancer (IBC), does not form a lump. Some of the symptoms of this condition can be similar to those of a breast infection, with warmth, tenderness, breast swelling, itching, and ridged thickened skin.


Laboratory tests

Laboratory tests for breast cancer can be broken down into groups, based on the purpose of testing.

Genetic risk:
BRCA-1 and BRCA-2 gene mutation – Women who are at high risk because of a personal or strong family history of early onset breast cancer or ovarian cancer can find out if they have a BRCA gene mutation. A mutation in either gene indicates that the person is at significantly higher lifetime risk (between 50-80%) for developing the disease. It is important to remember, however, that only about 5% to 10% of breast cancer cases occur in women with a BRCA gene mutation. Genetic counselling should be considered both before testing takes place and after receiving positive test results.

Diagnosis: cytology and surgical pathology
When a radiologist detects a suspicious area (calcifications or a non-palpable mass) on a mammogram, or a lump has been found during a clinical or self-examination, a doctor will frequently request a biopsy. For a biopsy, a small sample of tissue is taken from the suspicious area of the breast so that a pathologist can examine the cells for signs of cancer. There are several types of biopsies (fine needle aspiration, needle biopsy, surgical biopsy) performed to first determine whether the lesion in the breast is benign or malignant. This determination will guide treatment.

Malignant cells show changes or deviations from normal cells. Signs include changes in the size, shape, and appearance of cell nuclei and evidence of increased cell division. Malignant cells can also distort the normal arrangement of cells within breast tissue. Pathologists can diagnose cancer based upon the observed changes, determine how abnormal the cells appear, and see whether there is a single type of change or a mixture of changes. These results help guide breast cancer treatment.

Needle aspiration evaluations are limited due to the small sample that is obtained. A tissue biopsy is often needed to determine if a cancer is early stage or invasive. When a breast cancer is surgically removed (see Treatment), cells from the tumour and sometimes from adjacent tissue and lymph nodes are examined by the pathologist to help determine how far the cancer has spread.

Determine treatment options:
If the pathologist's diagnosis is breast cancer, there are several tests that may be performed on the tissue cancer cells. The results of these tests provide a prognosis and help the oncologist (cancer specialist) guide the woman's treatment. The most useful of these are HER-2/neu and oestrogen receptors and progesterone receptors.

  • HER2/neu is an oncogene associated with cell growth. Normal epithelial cells contain two copies of the HER2/neu gene and produce low levels of the HER2 protein on the surface of their cells. In about 20-30% of invasive breast cancers, the HER2/neu gene is amplified and its protein is over-expressed. These tumours are susceptible to treatment that specifically binds to this over-expressed protein. Drugs that target HER2 include, for example, trastuzumab (Herceptin®). Women with amplified HER2/neu gene respond well to these drugs and have a good prognosis.
  • Oestrogen and progesterone receptor (ER and PR) status are important for predicting the course of the disease and helping to guide treatment. Breast cancer cells that have estrogen and/or progesterone receptors can bind estrogen and progesterone. These female hormones promote cell growth and can "feed" ER- and PR-positive cancers. The higher the percentage of cancer cells that are positive, as well as the greater the intensity (the number of receptors per cell), the better the prognosis. This is because hormone-dependant cancers frequently respond well to hormonal therapy that blocks estrogen or lowers estrogen levels.

Breast cancer cells that are negative for HER2/neu amplification and negative for oestrogen and progesterone receptors are called "triple-negative." This type of breast cancer occurs more often in younger women and in women of African or Hispanic descent. Women with triple negative breast cancer may be predisposed to BRCA mutations.

Triple negative breast cancers tend to grow and spread more quickly than other types and have a worse prognosis. Because the cells do not have amplified HER2/neu, they will not respond to treatment with trastuzumab (Herceptin®). Likewise, they do not have receptors for oestrogen and progesterone and cannot be treated with therapy that blocks the hormones. However, they may be treated with other types of chemotherapy.

Monitor treatment:
Cancer antigen 15-3 (CA 15-3) – this is a protein that is produced by normal breast cells. There is an increased production of CA 15-3 in many women with breast cancer. CA 15-3 does not cause cancer. Rather, the protein is shed by tumour cells and enters the blood, making it useful as a tumour marker to follow the course of the cancer. CA 15-3 is elevated in only about 10% of women with early localised breast cancer but is elevated in about 80% of those with metastatic breast cancer. Blood tests for CA 15-3 may be ordered at intervals after treatment to help monitor a woman for breast cancer recurrence. They are not used as screens for breast cancer but can be used to follow it in some women once it has been diagnosed.

Non-laboratory tests

In addition to laboratory tests, there are non-laboratory tests that are equally important.

  • Mammography is widely recommended as a screening tool. A screening mammogram uses X-ray technology to produce an image of the breasts and can reveal breast cancer up to two years before a lump is large enough to be felt during a clinical or self-examination.
  • Digital mammography may yield a clearer image than a plain film mammography in some cases.
  • Younger women, whose breast tissue is often too dense to show tumours clearly on the X-ray film used for a standard mammogram, may benefit from ultrasound examination or rarely, magnetic resonance imaging (MRI).
  • Ductal lavage is an experimental technique in which the doctor extracts cells via a tiny tube inserted through the patient's nipple. Trials have been undertaken in the US but more evidence will be required before it is known whether this will be a useful test for breast cancer.
For more information on mammography and other imaging technologies, go to Better Health ChannelJean Hailes Foundation for Women's HealthBreastScreen Australia


Screening for breast cancer

Early breast cancer detection has a strong influence on breast cancer survival. For example, when breast cancer is found in the early, localized stage, 98.5% of those people survive for at least five years after diagnosis. The primary early detection tool is a mammogram.

The medical community recognises the value of breast cancer screening and mammography, but there is no universal consensus on how often it should be done or when it should be started. Most health organisations agree, however, that women should work with their doctor to assess their personal risk of developing breast cancer and to determine what is best for them. Considerations can be given to the benefits of screening as well as the harms. While screening can detect cancer early when it is most treatable, it may also lead to false-positive results and unnecessary follow-up procedures, such as biopsies.

Women with certain risk factors may be advised to begin screening at an earlier age and may be advised to be screened more frequently, with additional testing such as imaging scans.

Early detection of breast cancer gives the best possible chance of survival. The earlier an abnormality is found, the greater the number of effective treatment options. In Australia, free routine mammographic screening is available in each state for women aged 50 to 74 through BreastScreen Australia. Women 40 to 49 years old can also have mammograms, however breast screening is less effective for women under 40 years old. The density (thickness) of breast tissue makes it more difficult to see a cancer in an x-ray and fewer women are diagnosed in this age group.

Breast cancer may be divided into several stages, reflecting the size of the tumour and the extent to which the cancer has spread in the body. Determining the stage of a cancer can assist in treatment decisions and establishing a prognosis, i.e., predicting the course of the disease and the chances of remission and/or recurrence.
Stage Size of the tumour Location
Stage 0   Confined within the breast ducts (ductal carcinoma in situ, DCIS) or confined within the lobules (lobular carcinoma in situ, LCIS)
Stage I Less than 2 cm (3/4 inch) across Tumour has spread beyond the ducts but is still confined within the breast tissue
Stage IIA Less than 2 cm across or no tumour Spread to one to three lymph nodes in the armpit (axilla)
Between 2 and 5 cm (3/4 to 2 inches) across No spread to the lymph nodes
Stage IIB 2  to 5 cm across Spread to the lymph nodes
Larger than 5 cm across No spread to the lymph nodes
Stage IIIA   Spread to lymph nodes in the armpit that are attached to each other or other structures and may have spread to lymph nodes behind the breast bone
Stage IIIB Any size Spread to chest wall or skin of the breast; may have spread to lymph nodes in the armpit and may have spread to behind the breast bone
Inflammatory breast cancer, a rare type of cancer that does not form a lump, usually falls into this category because it is aggressive.
Stage IIIC Any size Spread to lymph nodes in the armpit and to lymph nodes either behind the breast bone or above the collar bone
Stage IV Any size Spread to distant organs such as bone or liver
Reccurrent Any size Breast cancer that was undetected aftre treatment but is now detectable in any area of the body


Many breast cancers are treated by removing as much of the cancer as is possible, and then using one or more other therapies to kill or control any remaining cancerous cells. A lumpectomy removes the cancerous tissue while leaving the remaining breast tissue intact. A mastectomy is a more extensive procedure but can still vary in the amount of the breast removed. While mastectomy was once the preferred treatment even in early stage breast cancer, more choices have become available. Now, lumpectomy followed by radiation has been demonstrated to be as effective as a mastectomy in treating early stage breast cancer. In performing either a lumpectomy or mastectomy, a doctor may remove some or all of the lymph nodes under the arm to help assess whether the cancer has spread.

There is a great deal of new research being performed in the field of breast cancer treatment, and your doctor is your best source of information.

Breast cancer tissue banks
Tissue banks also collect breast cancer samples, and information about the women who donate them, for use in breast cancer research. If you agree to participate, you will be asked to complete consent forms. You might be asked for consent before your surgery by a letter or in person. A small amount of your breast cancer tissue will be given to the tissue bank. This will not jeopardize the amount of tissue required by the pathologist for your pathology reporting.

Related web pages

On this site
Tests: BRCA, Tumour markers, CA 15-3, Her-2/neu, Hormone receptor status
Screening: Tests for young adults/adults: breast cancer

Elsewhere on the web
BreastScreen Australia
Jean Hailes Foundation for Women's Health
Healthdirect Australia: Breast cancer
Healthdirect Australia: Breast cancer awareness
RCPA Breast cancer pathology fact sheet

New References
Breast Cancer Network Australia.
Breast cancer Network Australia. http//
Breast Cancer Network Australia.
Breast cancer Pathology Fact Sheet.

Primary references from Lab Tests Online US