Why should I be screened?

Breast cancer is the most common cancer in New Zealand women. Over 600 women die from it each year and as we get older, our risk increases.

Breast cancer is the most common cancer in New Zealand women. Over 600 women die from it each year and as we get older, our risk increases.

In New Zealand eligible women from 45 to 69 can choose to join the BreastScreen Aotearoa (BSA) programme and 72 percent of women in this age group have done so.

But the earlier breast cancer is found, the better your chances of surviving. Screening won’t stop you from getting breast cancer, but it could reduce your risk of dying from it.

I don’t have a family history of breast cancer. Do I still need to be screened?

Yes you do. Most women who develop breast cancer have no close relative with the disease.  That’s why it’s so important, whether you have a family history or not, to have your checks and to have them regularly, every two years.

There is a large amount of international medical evidence that the number of deaths from breast cancer is reduced where there is organised breast screening. A study of the New Zealand programme currently under way will add to the available information.

The chance of a New Zealand woman getting and dying from breast cancer for every 10,000 women is shown in the table below.

Breast screening and effective treatments mean most women who get breast cancer do not die from it.

Analysis of developing or dying from breast cancer


Chance of developing or dying from breast cancer

For every 10,000 women 45-49 50-54 55-59 60-64 65-69
The chance of developing breast cancer is 22 24 26 33 34
The chance of dying from breast cancer each year without screening is 4 5 7 7 9
The chance of dying from breast cancer each year with screening is 3 3 3 5 5

Source: Ministry of Health. Data are averages for 2005-2009 incidence and mortality.

All BreastScreen Aotearoa facilities have to meet the BreastScreen Aotearoa National Policy and Quality Standards.  These are independently checked.  BSA monitoring reports can be viewed here.

The harms of breast screening

As with all screening tests, breast screening can have outcomes that women may consider harm.

  • Anxiety, inconvenience and discomfort

You may need to have more tests if there was something on your mammogram that needed to be checked out. You will need to come in for another appointment. This can be inconvenient and sometimes the additional tests are uncomfortable. While most women returning for further tests aren’t found to have breast cancer, this can still be a worrying time.

  • Radiation

All X-rays, including mammograms, mean you are exposed to a small amount of radiation, but the amount is so small it is unlikely to cause you any harm.

  • Overdiagnosis

It is possible a mammogram could find a breast cancer that would never have caused problems during a woman’s lifetime. Unfortunately it is not possible to tell the difference between cancers that will or won’t cause problems.

  • Overtreatment

If a breast cancer is found you will be offered treatment. There is a possibility you may have treatment for a breast cancer that would not have been detected during your lifetime without screening.

  • Despite having mammograms every two years, breast cancer might still be missed. This could be because some cancers don’t show up on a mammogram (false-negative test), the radiologist (X-ray doctor) may not pick up the cancer (false-negative test), or it might be very fast growing (interval cancer).

Despite these harms, mammograms are the only proven way of finding breast cancers early enough to reduce your risk of dying of breast cancer.

More information about the harms of breast screening can be found in the Addressing the harms of population breast screening position statement.

Page last updated: 27 November 2014
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