Having a mammogram

An MRT (medical radiation technologist) or radiographer will place your breast between two plates on the mammogram machine. The breast is then flattened to spread the tissue apart. This gives a clearer view, and pressing the breast flatter means less radiation is needed. Some people find this a bit uncomfortable, but it doesn't last long. It’s best to go for a mammogram after your period has finished and any breast tenderness has settled.

They'll usually take two views of each breast, one from the side and one from above. The images are reviewed by two radiologists (specialist doctors who use medical imaging to diagnose disease) who write a report on what they find. If anything abnormal is found, you will be asked to come back for more tests.

BreastScreen Aotearoa (BSA) is New Zealand's free national breast screening programme. They provide free mammograms every two years for women with no symptoms aged between 45 and 69. From October 2025, BreastScreen Aotearoa began a phased roll out to increase the screening age to 74.

BSA provides mammograms at its clinics and mobile screening units.

Visit the BreastScreen Aotearoa website to find out where to have your mammogram.

Screening mammograms can also be done at:

• Private x-ray clinics
• Private breast clinics
• Public hospitals (only for women who are at high risk. Surveillance screening is done for women who have previously had breast cancer.)

You may wish to have a support person or whānau member go with you.

To find out more about what to expect when you go for a mammogram, see Health New Zealand, Te Whatu Ora’s “Having a mammogram: What you need to know page"

BreastScreen Aotearoa provides free mammograms for women with no symptoms of breast cancer, between the ages of 45–69. Eligibility is gradually being extended to 74. You can check your eligibility here or call BreastScreen Aotearoa on 0800 270 200.

Private mammograms are usually tomosynthesis mammograms which provide a 3D image of the breast. It’s worth shopping around, as prices vary between clinics.

BreastScreen Aotearoa uses a national screening system called Te Puna to identify eligible women and send invitations or reminders through a secure personalised link (by email, text or letter).

If you think you are eligible and have not received an invitation, contact BreastScreen Aotearoa on 0800 270 200.

Most private breast clinics and family doctors also have a recall system, but it pays to ask for a reminder at reception to ensure you receive one.

A diagnostic mammogram is used to examine a breast change or take a closer look at something found during screening. It usually includes additional images from different angles or enlarged views of a particular area. Other tests, such as an ultrasound or biopsy, may also be needed.

Read more about diagnostic mammograms (The Triple Test).

Dense breast tissue appears white on a mammogram. Because breast cancer can also appear white, it can make cancer harder to see on a mammogram if you have dense breasts. Breast density isn’t something you can see or feel, it can only be assessed from a mammogram.

Dense breasts are more common in younger women, which is why mammograms aren’t routinely used for breast screening in young women under 40. However, mammograms may be recommended for younger women at high risk because of their family history or a known gene change.

Women with high breast density may also be recommended to have annual rather than two-yearly screening.

Breast cancers that are diagnosed between breast screening tests are called interval cancers. In some cases they may have grown quickly, or they may have been present but not detected on the last screening.

Unfortunately, there is no foolproof breast screening method. Normal breast tissue can sometimes mask a breast cancer so it can't be seen on a mammogram, and occasionally a detectable cancer will be missed. This is known as a false negative result.

Mammograms can also identify an area that looks like cancer, but further testing proves it to be benign (not cancer). This is a false positive result.

Being recalled for further tests can be worrying, but most people who are recalled will not be diagnosed with breast cancer.

Mammograms use a small amount of radiation. For most women, the benefits of finding breast cancer early outweigh the very small risk from this radiation.

Ultrasound is useful for taking a closer look at something unusual found on a mammogram or breast check, but it isn’t generally recommended as a replacement for screening mammograms.

It’s very good at picking up things that might be a problem, but it’s not as good as a mammogram at telling the difference between something harmless and something that needs more testing.

Ultrasound also doesn’t usually pick up tiny calcium deposits (calcifications), which can sometimes be an early sign of cancer.

MRI (magnetic resonance imaging) of the breast uses a powerful magnet, radio waves and a computer to produce detailed images of the breast. An injection of a contrast medium (gadolinium) is often used to help detection. MRI is mostly used alongside mammograms and ultrasound, rather than on its own. It is often used to assess the size and location of a breast cancer, and if there are any other areas of concern.

MRI may be recommended alongside a mammogram for women who are at high risk of breast cancer due to family history or known gene mutation, but is not generally used in regular breast screening. It’s a costly procedure that takes more time to perform than other tests and requires specially trained radiologists to review the images.

Benefits

There is a lot of research to show the benefits of breast screening outweigh the harms. Mammograms can:

• Find breast cancer before it can be seen or felt
• Increase the chance that breast cancer is diagnosed at an earlier stage
• Reduce the risk of dying from breast cancer
• Allow some people to have less extensive treatment.

Potential harms

• Overdiagnosis - Breast screening might diagnose some slow growing cancers which may never have caused any harm over a person's lifetime. This is known as overdiagnosis. Unfortunately, there is currently no way for doctors to know which cancers fall into this category.
• Exposure to small amounts of radiation.
• Anxiety caused to women who are recalled for further testing but are found not to have cancer.

For most women who are eligible for screening, the benefits of regular mammograms outweigh these possible harms.