Breast cancer causes

Breast cancer can occur at any age, but it is most common in women over the age of 60. Around one quarter of women who are diagnosed with breast cancer are younger than 50.

Men can also develop breast cancer, although this is extremely rare. Each year, about 25 men are diagnosed in Victoria. It is treated in the same way as breast cancer in women.

There are different types of breast cancer, but they all begin in the milk ducts or the milk lobules (or both). Some breast cancers are found when they are ‘in situ’. This means that they have not spread outside the milk duct or lobule where the cancer began.

Most breast cancers are found when they are ‘invasive’. This means the cancers have grown beyond the duct or lobule, where they began, into other breast tissue, or spread to other parts of the body. Breast cancer that spreads out of the breast may spread to lymph nodes in the armpit nearest the breast affected by cancer (axillary lymph nodes). It can also spread to other parts of the body, such as the bones, lungs and liver.

Risks and causes of breast cancer

The exact cause of breast cancer is unknown, but factors that seem to increase risk include:

• gender – being a woman
• getting older – women over 50 years of age are invited to take part in yearly mammograms to screen for breast cancer (women from the age of 40 are also able to access yearly mammograms)
• heredity – having several close family members (mother, sister or daughter) who have had breast cancer
• previous history of breast cancer – women who have had breast cancer have a greater risk of developing it again
• certain breast diseases – some types of breast disease that are found through mammograms indicate an increased risk.

Other risk factors for breast cancer

Other factors that seem to increase risk include:

• not having children or having children after the age of 30
• early age at first period
• later age of natural menopause (55 years or older)
• alcohol intake (more than one standard drink per day)
• obesity or gaining a lot of weight after menopause
• using the contraceptive pill – the risk is higher while taking the pill and for about ten years after stopping use
• using hormone replacement therapy (HRT) – also known as hormone therapy (HT) – the risk increases the longer you take it, but disappears within about two years of stopping use.

Having some of these risk factors does not mean that you will get breast cancer. Most women with breast cancer have no known risk factors, aside from getting older. More research needs to be done before we can be definite about risk factors.

In men, the main risk factor is abnormal enlargement of the breasts (gynaecomastia) due to drug, chemical or hormone treatments. Men with Klinefelter’s syndrome (a sex chromosome disorder) can also be at risk. A man’s risk increases where there is a family history of male breast cancer or a strong family history of breast cancer.

The risk of breast cancer for transgender individuals varies depending on their situation. Transwomens’ risk factors are the same as for men, unless they have had or are having hormonal supplements, in which case, their risk of developing breast cancer is the same as the general population of Australian women. Transmens’ risk factors remain the same as for the general population of Australian women, unless they have had a mastectomy and then their risk is reduced.

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Check your breasts

Breasts undergo many changes during a woman’s life. These changes can be due to puberty, the menstrual cycle, pregnancy, breastfeeding or changes in weight or ageing. It is important for all women to get to know the normal look and feel of their breasts.

By regularly checking your breasts, you may be able to recognise changes that could be a sign of breast cancer. Such changes include:

• thickening of the tissue
• a lump or lumpiness
• discharge from the nipple
• an inverted or ‘turned-in nipple’ (unless the nipple has always been turned in)
• puckering or dimpling of the skin
• a change in the shape of the breast or nipple
• a painful area
• anything that is not ‘usual’ for you.

Some of these symptoms can occur without any serious disease being present. Nine out of 10 breast changes are not breast cancer. However, just to be sure, your doctor should check any unusual breast change.

Screening mammography

Screening mammography is provided as a free service for women aged 50 to 74 through the BreastScreen Australia program. It is used to detect breast cancer early, when you are well and have no obvious breast symptoms. Screening mammograms can detect breast cancers that are too small to be felt by you or your doctor.

Mammograms taken at different times can later be compared to show changes in breast tissue over time. Screening is open to women from the age of 40 and can continue after the age of 74, however reminders are only sent to those who are between the ages of 50 and 74 years).

Diagnosis of breast cancer

Breast changes are investigated through a series of tests organised by your doctor or specialist. Most breast changes are diagnosed as benign (non-cancerous). If your tests show that you may have cancer, your doctor will refer you to a specialist who will advise you about treatment options.

Initial tests you may have include:

• physical examination – breasts and armpits are examined
• diagnostic mammogram – an x-ray of the breast tissue
• ultrasound – a device that uses sound waves to scan the breast.

If further tests are required, one or more procedures may be used, including:

• Fine needle aspiration – a very narrow needle is used to withdraw cells from the testing area.
• Core biopsy – a larger needle is used to take a tissue sample for testing.
• Open biopsy – surgery is performed under general anaesthetic to remove the whole area for testing.
• Hormone tests – if a cancer is found, it can be checked for special markers called hormone receptors to see if it will respond to hormone treatment.
• Ductogram (also known as a galactogram) or discharge test – this is for breast cancers that are causing a discharge from the nipple.

Other tests may include blood tests, bone scans and chest x-rays. Test results can take a few days to come back. It is very natural to feel anxious while waiting to get your results. It can help to talk to a close friend or relative about how you are feeling. You can also contact the Cancer Council Helpline on 13 11 20 and speak with a cancer nurse.