Breast cancer is the third most common cancer in Hong Kong.
Breast cancer is rare in men, with around 15 new cases diagnosed in Hong Kong in 2014, compared with around 3,868 new cases in women.
Only three per cent of breast cancer cases are in women who carry genes that have been linked to the disease. Many of the factors that increase your chances of developing the disease are linked to your lifestyle.
What is breast cancer?
Breasts are made up of fatty connective tissue, milk-producing glands and ducts that carry milk from the glands to the nipple. Breast tissue naturally develops in response to hormones at different stages of life – for example, during puberty, pregnancy and breastfeeding.
Breast cancers almost always develop in the glands or ducts that produce milk and carry it to the nipple.
Cancers develop as a result of cells being damaged, which then grow uncontrollably, forming a lump or thickening called a tumour.
There are many different reasons why breast cancers develop, and hormones (particularly oestrogen) can influence the development and growth of some breast cancers. This means that life events that affect your hormone levels, such as pregnancy, can alter your cancer risk.
There are also important risk factors that you can do something about, such as your diet and lifestyle choices.
Who is most at risk of breast cancer?
As with all cancers, the risk of developing breast cancer depends on a number of factors and varies from person to person.
Lifestyle risk factors
- Drinking alcohol
- Being overweight or obese (for post-menopausal breast cancer only)
- Not doing enough physical activity
- Not breastfeeding when you have a baby
Other risk factors
- Age – your risk increases as you get older
- Starting your period early (before age 12)
- Going through menopause late (over age 55)
- Not having children, or having a first pregnancy over the age of 30
- Family history – particularly if a close relative was diagnosed before the age of 50. If you are concerned about this, we recommend you speak to your doctor
- Height – taller women are at greater risk of breast cancer
- Taking combined hormone replacement therapy (the evidence is less clear for oestrogen-only HRT) – risk slightly increases the longer you take HRT, but decreases gradually once you stop
- Taking the oral contraceptive pill (the evidence is less clear for the mini pill) – risk slightly increases when you take the pill, but slowly returns to normal after you stop
If any of these apply to you, it does not mean that you will develop breast cancer – it just means that your risk may be higher than average. The good news is that there are steps you can take to reduce your risk.
How can you reduce your risk of breast cancer?
These steps are based on research from our Continuous Update Project (CUP).
There is strong evidence that drinking alcohol increases breast cancer risk. In fact, one in five breast cancers could be prevented if we didn't drink alcohol. Find out more about the link between alcohol and cancer or find out how many calories are in alcoholic drinks by using our alcohol calorie calculator.
Being a healthy weight is one of the most important things you can do to help protect against breast cancer – 1 in 6 breast cancer cases could be prevented if everyone was a healthy weight. Try our Body Mass Index calculator to see if you are a healthy weight for your height.
Vigorous physical activity lowers the risk of pre-menopausal breast cancer and every type of physical activity (moderate and vigorous reduces the risk of post-menopausal breast cancer. We recommend being physically active for at least 30 minutes every day, and to sit less. The more active you are the better – try our exercise calorie calculator for more ideas.
Breastfeeding is good for your baby’s health and it can also help protect you against breast cancer. Find out more about our breastfeeding for cancer prevention recommendation.
What about screening?
The good news is that most breast cancer cases can be successfully treated if they are detected early. For more information about screening for breast cancer, please visit www.chp.gov.hk.