In Australia, breast cancer is the most common type of cancer affecting women apart from non-melanoma skin cancer, with about one in seven women expected to be diagnosed with breast cancer during their lifetime (Cancer Council Victoria 2022).
It’s also possible, albeit rare, for breast cancer to affect men, with about 160 men diagnosed every year. Trans women, trans men, non-binary and gender-diverse people may also be at risk (Cancer Council Victoria 2022).
Every person has breast tissue. In people who were assigned female at birth, the breasts comprise lobes, lobules and ducts (Cancer Council Victoria 2022).
Each breast contains between 12 and 20 sections known as lobes. Each one of these lobes contains glands known as lobules that produce milk. Lobes and lobules are connected by thin tubes known as ducts, which carry milk to the nipples (Cancer Council Victoria 2022).
People who were assigned male at birth have ducts, but very few (or even no) lobes and lobules.
Everyone’s breast tissue contains fibrous or fatty tissue (Cancer Council Victoria 2022).
What is Breast Cancer?
Breast cancer occurs when cells that line either the breast ducts or lobules begin to grow abnormally (Cancer Council Victoria 2022).
The exact cause of this abnormal cell growth is not known, but there are identified risk factors (Better Health Channel 2023).
Risk Factors for Breast Cancer
Factors that increase the risk of breast cancer include:
In assigned female at birth people:
Older age (over 50)
Having dense breast tissue (as seen on a mammogram)
Family history of breast cancer or a certain type of ovarian cancer in a first-degree relative (e.g. mother or sister) or in female relatives on the same side of the family (especially if they were diagnosed at a young age)
Being overweight or gaining weight after menopause
Excessive alcohol consumption
Early commencement of menstruation (before the age of 12)
Giving birth after the age of 30
Never giving birth
Starting menopause after the age of 55
Certain medicines and treatments:
Taking menopause hormone therapy (MHT) that contains oestrogen and progestogen
Taking the contraceptive pill for a prolonged period of time
Taking diethylstilboestrol (DES) while pregnant
Undergoing radiation therapy to the chest for Hodgkin lymphoma
Atypical ductal hyperplasia or proliferative disease without atypia
Previous diagnosis of lobular carcinoma in situ (LCIS) or ductal carcinoma in situ (DCIS).
In assigned male at birth people, risk factors may include older age, Klinefelter syndrome, and family history (Cancer Council Australia 2022).
(Cancer Council Australia 2022; Better Health Channel 2023)
In assigned male at birth people:
Klinefelter syndrome (a rare genetic disorder where an assigned male at birth person has three sex chromosomes - XXY)
Having several first-degree relatives who have been diagnosed with BRCA2 breast cancer
Family history of breast cancer diagnosed under the of 40
Having several relatives who have been diagnosed with ovarian, colon or prostate cancer.
(Cancer Council Australia 2022)
Signs of Breast Cancer
It’s normal for the breasts to change over time, and while most changes are not caused by cancer, there are some signs that may be indicative of cancer and should be investigated (Better Health Channel 2023). These include:
A lump, lumpiness or thickening in the breast (particularly if only in one breast)
Changes in the shape or size of the breast
Nipple changes (e.g. shape, crusting, sores or ulcers, redness, clear or bloody discharge)
Skin changes on the breast (e.g. dimpling, indentation, rash, scaliness, redness or changes in colour)
Swelling or discomfort in the armpit
Prolonged, unusual pain in one breast only that is unrelated to menstrual cycle symptoms.
(Cancer Council Australia 2022)
Breast Cancer Screening
Under the national BreastScreen Australia program, women aged between 40 and 74 are able to access a free mammogram (breast screen) every two years (DoHaAC 2023).
Screening can detect breast cancer early, even before it’s seen or felt (DoHaAC 2023).
(Cancer Council Australia 2022; Better Health Channel 2023; Healthdirect 2020)
Breast Cancer in Trans and Gender-diverse People
Every person has breast tissue (unless it has been removed). This includes men, as well as trans and gender-diverse people (BreastScreen Victoria 2023).
Trans women (or gender-diverse people who were assigned male at birth) who have been receiving gender-affirming hormones (e.g. oestrogen) for more than five years may be at increased risk of breast cancer and should be screened every two years.
Trans men (or gender-diverse people who were assigned female at birth) who have not undergone subcutaneous mastectomy (top surgery) are recommended to undergo screening every two years. Trans men who have undergone top surgery are encouraged to consult with their general practitioner about their individual risk factors.
(Cancer Council Victoria 2022; BreastScreen Victoria 2022; Mayo Clinic 2022)
It’s important to note that trans and gender-diverse people are underscreened for breast cancer due to a variety of barriers that deter them from accessing this care. These barriers include:
Ignorance from staff
Fear of being misgendered or needing to ‘out’ themselves
Lack of awareness about screening
Fear of experiencing gender dysphoria or anxiety due to the test.
(BreastScreen Victoria 2022)
Therefore, it’s important to ensure that breast cancer screening and care is inclusive, welcoming and safe for all patients (BreastScreen Victoria 2022).
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