If you’ve had a privately booked mammogram, you've taken an important step in caring for your health. Research has found (2022) that, compared to waiting until 50 for routine NHS screening, regular breast screening from the age of 40 can help spot signs of early breast cancer much earlier and improve treatment outcomes.

However, whether you’re waiting for NHS or private results, it’s perfectly natural to feel anxious.

If you’re waiting for a routine mammogram screening to come back, you’re not alone in wondering what the results may be and how to understand the report you receive, particularly the M1 to M5 results that appear in your mammogram results letter.

This guide will give you an idea of what results may come back, from normal, healthy breast tissue with no abnormalities to the possibility of finding cancer.

What do routine mammogram results involve?

Once you’ve had your mammogram screening, your radiologist will carefully examine the images to look for any abnormalities in the tissue or structure of your breast. You will likely receive one of two types of results:

No sign of breast cancer: This means there are no signs of cancer in your mammogram, and you have the all-clear until your next routine breast scan.
Need further tests: Sometimes, your radiologist may see something that requires a closer look. While this may sound worrying, it’s important to remember that most people who need further tests won't be diagnosed with breast cancer.

If you’re called back for more tests, try to remember that this is a normal part of the screening process for many people. The additional tests will help your doctor get a clearer picture of your breast health. Spotting anomalies early is crucial because it helps you access treatment earlier, which can mean a better outcome.

What is a mammogram results letter?

A mammogram results letter explains the findings of your breast screening. It may arrive by post within a week or two of your mammogram, or you may receive the results by email.

The letter will include the date of your mammogram, a summary of the findings, and information on whether you have the all-clear until your next screening or need additional tests.

If your mammogram results show an urgent finding, the experts at your selected scanning centre will call you to explain the results and any next steps, such as further tests.

While an urgent finding might sound scary, it’s important to bear in mind that it doesn’t mean cancer. In fact, according to Cancer Research (2024), more than 9 in 10 people who receive an urgent cancer referral are not diagnosed with cancer. What it does mean, though, is that if there is cancer in the breast, it is more likely to be caught and treated earlier.

What can I expect from my mammogram results?

Your results will be described using a letter and number system. The letter M stands for mammogram and the numbers 1 to 5 stand for the finding. Your radiologist will classify the findings of your breast screening into five levels of ‘suspicion’ that cancer may be present in the breast. Here’s what each classification means:

M1 (Normal breast tissue): Your results show normal and healthy breast tissue; no further tests or screenings are needed until your next routine screening.
M2 (Benign): Your results show that some changes have been identified, but they are not considered cancerous. You should follow your doctor’s recommendations for any necessary follow-up.
M3 (Uncertain but probably benign): Your results show changes that are not likely to be cancerous, but you may need further tests or repeat mammograms to be sure. Follow your doctor’s recommendations for the next steps.
M4 (Suspicious and possibly cancer): Your results show changes that may possibly be cancerous. You’ll need to speak to your doctor promptly about your next steps, which could include additional tests such as a breast examination, repeat mammograms, ultrasound scans and a biopsy.
M5 (Highly suspicious and probably cancer): Your results show changes likely to be cancerous. You’ll need to speak to your doctor immediately about the next steps, which could include the additional tests above and a referral to a cancer specialist.

How long do mammogram results take?

How long you’ll wait for mammogram results can vary based on your location and the scanning centre you visited, but generally, you can expect results within around two weeks of your screening.

How long does it take to get mammogram results if something is wrong?

Your local screening clinic should let you know when and how you'll get your test results. While some people may get mammogram results same day, this isn’t typical. However, be reassured that your clinic will communicate your results to you as quickly as possible to ensure any additional tests and treatment you need are carried out quickly.

When to worry about mammogram results?

Receiving your mammogram results can be a worrying time, but it’s important to remember that not all findings are cause for concern. Having an M1 or M2 result generally means that you have normal and healthy breast tissue.

If your results indicate something that needs a closer look or further tests, you will be contacted directly by your scanning centre’s breast specialist. They will provide advice and guidance on the next steps, including how to reach out to your GP if you have any concerns or questions. Just remember that they are there to support you throughout the process.

What are the most common reasons for being recalled after a mammogram?

While most recalls are precautionary, here are the most common reasons for being recalled after a mammogram in the UK:

The images from your mammogram are blurred or unclear.
You’ve had a false positive result from your mammogram (more on this below).
Your breast tissue is dense, which makes it difficult to see some parts of the breast.
Your mammogram results look different from a previous mammogram.
You have areas of calcifications (small calcium deposits).
Your breast was compressed differently or in a different position than previous mammograms, making it difficult for your radiologist to see changes.
Your radiologist has identified cysts or benign lumps.
There is a suspicious area that needs further imaging or a biopsy.

A false positive mammogram will look abnormal in the results despite there being no cancer present. It’s more likely to happen if you’re young, have dense breast tissue, have had breast surgery, or you’re taking hormone replacement therapy.

For example, in 2020-21, 4% of women aged 45 and over who had a mammogram received an abnormal result, meaning they needed further tests. But, after these tests, 77.1% of these women (36,358) did not have breast cancer. False alarms (called false positives) can happen, but it is still important to undergo your routine mammograms and keep in mind that being recalled does not automatically mean you have cause for concern.

Is no news good news after a mammogram?

Be reassured that you will always receive the results from a mammogram, whether normal or containing any anomalies that need to be looked at. Even if you don’t hear straight away, try not to worry. Most results from mammograms show normal, healthy breast tissue.

How fast can breast cancer develop between mammograms?

Breast cancer can develop at different rates, and it’s possible for a cancer to grow between routine mammograms, which are usually every 3 years in the UK for women aged 50 to 71. This is why regular screenings are important to detect changes early. If you're over 40 and prefer more frequent checks, you can opt for annual mammograms privately through services like Scan.com. Knowing that you have closer monitoring will help you have peace of mind between NHS screenings.

Normal vs abnormal mammogram images

A normal, healthy mammogram (M1 or M2) will show smooth, even breast tissue images without any unusual lumps, masses, or abnormalities. Calcifications or benign cysts may appear but will have rounded and smooth edges - these are considered to be benign.

An abnormal mammogram that needs further testing (M3 to M5) may show irregular shapes, white patches or masses with jagged edges, or clusters of calcifications in breast tissue.

Why breast Screening results are important

Mammograms are crucial in detecting breast cancer early, often before any symptoms are present. This means that your treatment will be more effective and you’re likely to have a better outcome. Your first mammogram will be a useful baseline tool against which future mammograms can be compared for changes. With regular screenings, even small changes can be detected, diagnosed and dealt with quickly.

If you're over 40 and you want to take control of your breast health, book a mammogram today through Scan.com. Not only will you have the option for closer monitoring between routine NHS screenings, but you can also have a consultation with a clinician - without any obligation to book a mammogram afterwards. You’ll also have the expert support and guidance of fully-trained specialists at our industry-leading partner scanning centres.