Women and men both have breast tissue.
In women, breasts are made up of milk glands. A milk gland consists of:
In men, the development of the lobules is suppressed at puberty by testosterone, the male sex hormone.
Both female and male breasts contain supportive fibrous and fatty tissue. Some breast tissue extends into the armpit (axilla). This is known as the axillary tail.
The lymphatic system is part of the immune system and protects the body against disease and infection. It is made up of a network of thin tubes called lymph vessels. These connect to groups of small, bean-shaped structures called lymph nodes or glands.
Lymph nodes are found throughout the body, including the armpits (axillary), the breastbone, the neck, abdomen and groin.
Breast cancer occurs when the cells lining the breast lobules or ducts grow abnormally and out of control. A tumour can form in the lobules or ducts of the breast.
Women and men can both get breast cancer, although it is rare in men.
There are several types of breast cancer.
The most common types are invasive ductal carcinoma (IDC) and invasive lobular carcinoma (ILC).
Some women have abnormal cells in the lobules of the breast. This is called lobular carcinoma in situ or LCIS. This is not cancer. While LCIS increases the risk of developing cancer, most women with this condition will not develop breast cancer. Your medical team will monitor you with regular mammograms or other types of breast imaging.
Breast cancer is the most common cancer in Australian women, representing 28% of all cancers in women. About 14,000 women are diagnosed each year. One in eight women will be diagnosed with breast cancer by the age of 85.
Although it can occur at any age, breast cancer is more common in older women. More than two in three (69%) are diagnosed in women aged 40–69. About one in four (25%) are diagnosed in women aged 70 and over. Nearly 80% of women diagnosed had IDC, while about 11% had ILC.
About 130 men are diagnosed in Australia each year. This represents less than 1% of all breast cancers.
Some people have no symptoms but if you do, you may notice a change in your breast or your doctor may find an unusual breast change during a physical examination.
Signs to look for include:
Breast changes don’t necessarily mean you have cancer. However, if you have any symptoms, have them checked by your doctor without delay. Some women have no symptoms and the breast cancer is found on a screening mammogram.
In women, the exact cause of breast cancer is not known, but some factors increase the risk. These include:
Some lifestyle factors, such as being overweight or drinking more than one standard alcoholic drink a day, may also slightly increase the risk.
Having some of these risk factors does not necessarily mean that you will develop breast cancer. Most women with breast cancer have no known risk factors, aside from getting older.
In men, breast cancer usually occurs over the age of 60. It is most common in men who have:
Most women diagnosed with breast cancer do not have a family history of the disease.
However, a small number of women with breast cancer (about one in 20) have inherited a gene fault that increases their risk. The two most common breast cancer genes are called BRCA1 and BRCA2.
Everyone inherits a set of genes from each parent, so they have two copies of each gene. Sometimes there is a fault in one copy of a gene, which stops that gene working properly. This fault is called a mutation.
Women in families with an inherited gene change are at an increased risk of breast and ovarian cancer. Men in these families may also be at an increased risk of breast and prostate cancer.
People with a strong family history of breast cancer can be tested to see if they have inherited a gene change. If you would like to know more about genetic testing, talk to your doctor or breast care nurse, or call Cancer Council 13 11 20.
Information reviewed by: Dr Carolyn Cho, Breast and General Surgeon, Surgical Oncology, Deakin, ACT; Lynn Buglar, Breast Physician, BreastScreen, NSW; Mena Crew, Consumer; Elizabeth Jacobson, Consumer; Jane Marsh, Clinical Manager, Breast Centre, Brian Fricker Oncology Centre and Burnside War Memorial Hospital, SA; Marie Murdoch, Breast Care Nurse, Cancer Council Queensland, QLD; and Marion Strong, Clinical Nurse Consultant Breast Care Nurse and Cancer Care Coordinator, Toowoomba Hospital, QLD.