Breast awareness

Lower your risk of breast cancer

Since the cause of breast cancer is not fully understood, there is no way to definitely prevent it. However, making healthy lifestyle choices may reduce your chance of developing the disease.

We all make trade-offs in our lifestyle against our risk of various cancers – whether it’s how much alcohol we drink, or how much time we spend in the sun. Consider how the following factors affect your risk of breast cancer, and whether you need to make lifestyle modifcations to reduce your risk.

Excess weight after menopause

Women who are overweight or obese after menopause have a higher risk of developing breast cancer. After menopause, oestrogen is produced in fat tissue rather than in the ovaries, so women who are overweight have high oestrogen levels compared to women of a healthy weight.

Being overweight before menopause doesn't seem to carry the same risk. However, weight gained during that time is likely to carry over into the post-menopausal setting, so it is wise at any age to keep weight within a healthy range.

To maintain a healthy weight choose foods that are low in carbohydrates and sugars and those that contain beneficial non-saturated fats. It’s important to incorporate regular exercise into your lifestyle.

You can calculate your healthy weight range here:

https://www.healthnavigator.org.nz/bmi-calculator/

Physical activity

Many large studies have shown that engaging in regular physical activity can reduce your risk of developing breast cancer . Compared to women who are inactive, those who exercise for 3-4 hours a week can reduce their risk by 20-30%. Exercise can range from moderately intense activities such as brisk walking to vigorous activity such as jogging, gym workouts and other aerobic exercise.

You can also try to incorporate extra activities into your daily life:

Choose to walk or bike instead of driving

Take the stairs instead of the lift

Park further away from your destination and walk

Go for a brisk walk during your lunch break

Regular exercise helps you to maintain a healthy weight and can reduce the levels of oestrogen, insulin and insulin-like growth factors in your body. These substances all contribute to the growth of breast cancer cells.

Exercise also reduces the risk of recurrence following breast cancer treatment..

Alcohol consumption

Drinking alcohol has been firmly established as a risk factor for developing breast cancer. Alcohol changes the way the body metabolises oestrogen, causing blood oestrogen levels to rise. There is no safe level of alcohol consumption and as few as two drinks a day increases the risk of breast cancer.

Read the Cancer Society’s position statement on Alcohol and Cancer.

Use of combined hormone replacement therapy

Results from the Million Women Study ,the Women's Health Initiative Study and the Nurses Study showed that women taking combined hormone replacement therapy, using both oestrogen and progestogen, had an increased breast cancer risk during use and for 2-5 years afterwards. The longer you use it for, the higher your risk. Oestrogen-only HRT( prescribed for women who no longer have a uterus) is associated with little or no change in breast cancer risk.

If you are considering using HRT to control severe menopausal symptoms, talk to your doctor about the risks versus benefits. It is recommended that HRT use should be at the lowest possible dose to control symptoms, for the shortest possible time.

Oral Contraceptive Pill and Depo Provera use

The combined (oestrogen and progestin) oral contraceptive pill (OCP) slightly increases the risk of developing breast cancer, however this risk disappears within 10 years of stopping the pill. The increase in risk is slightly lower in women taking a progestin only pill.

OCP use is considered relatively safe for women under the age of 40 who are not already at high risk of breast cancer, and it reduces the risk of ovarian and endometrial cancers.

Depo Provera, an injectable progesterone, has been shown to slightly increase breast cancer risk but the increase in risk disappears after discontinuation of use.

Timing of childbearing – age at first birth, number of children and breastfeeding

Not having children or having your first child over the age of 30 increases your risk of breast cancer because of the continuous exposure to oestrogen during menstrual cycles. Having children at a younger age and having multiple children reduces the risk, as does breastfeeding, especially if you breastfeed continuously for at least a year. These factors are most strongly associated with the risk of oestrogen receptor positive breast cancer. The risk of triple negative breast cancer is reduced by breastfeeding but doesn't seem to be reduced by early age at first birth.

Although childbirth lowers your lifetime risk of breast cancer, it's important to know there is a short-term increase in risk for 2-5 years after giving birth. It's not something to stress about - breast cancer is less common in younger women -but it does mean you should take breast lumps or other changes after childbirth seriously, and insist on being referred for assessment if you're concerned.