How is the assessment conducted?

The X-rays are assessed carefully. To minimise the risk of errors, radiologists receive special training. Every X-ray is reviewed by 2 radiologists. They look at and assess each X-ray by themselves. In some cases, they will consult a third radiologist. For example, if the 2 radiologists disagree on the results.

If you have taken part in the population screening in the past, the radiologists will compare the new X-rays with the X-rays from your previous screening(s). That way, they can see if anything has changed. This can help them find anomalies early. It is important to note that no breast X-ray is exactly the same as the previous one. Staff are trained to take breast X-rays as consistently as possible. That is not always the case, because the breast is flexible.

What possible assessments are there?

The radiologists' assessments lead to the results that are in your letter. The possible results can be found on the Mammogram results page.

The following situations can occur:

1. Radiologist 1 sees no need to refer the participant. Radiologist 2 also sees that there is no need to refer the participant.

So they agree. The participant gets the result: No abnormalities found.

2. Radiologist 1 wants to refer the participant. Radiologist 2 also wants to refer the participant.

So they agree. The participant gets the result: An abnormality has been found, further examination is required.

3. One radiologist finds it necessary to refer the participant. The other radiologist does not consider it necessary to refer the participant.

So the radiologists disagree.

Radiologist 1 or Radiologist 2 re-examines the images. There are now two options:

• The radiologist concludes that referral is necessary. The participant gets the result: An abnormality has been found, further examination is required.
• The radiologist concludes that there is no need for referral. In that case, a new, third radiologist will be added to also review the breast X-rays. Radiologist 3 determines whether referral is necessary or not. The participant will receive the results given by Radiologist 3.

What is the radiologist looking for?

When reviewing the X-rays, the radiologists look for evidence of breast cancer. 
The radiologist will look for 4 different indications:

1. Mass. This is a spot that can be seen in both X-rays.
2. Calcifications. These are tiny spots (calcium deposits) in the breast tissue.
3. Asymmetry. The glandular tissue in the breast differs between the left and right breast.
4. Architectural distortion. This means the tissue in one breast has a different structure from that in the other breast.

What are some examples of abnormalities on the images?

It is quite common for abnormalities to be visible on the images. Very often, the radiologists determine that there is no cancer. In that case, the participant is not referred to the hospital.
Below are examples of abnormalities that radiologists determine are not cancer.

• Examples of a benign mass:
  • the spot on the image has a well-defined border and is grey rather than white. Especially if there are more similar spots, they are benign fluid-filled sacs (also called cysts);
  • the spot is already visible in previous images and has not grown in size;
  • the spot is caused by a wart or mole on the skin of the breast.
     
• Examples of benign calcifications:
  • the shape of the calcium deposits and their distribution across the breast(s) do not indicate breast cancer;
  • the calcium deposits are unchanged from previous X-rays.
     
• Examples of benign asymmetry:
  • the asymmetry is only visible in one of the two X-rays and the other image shows no abnormalities in the same area of the breast;
  • the entire glandular tissue of one breast looks different from the glandular tissue of the other, but without any suspicious spots. This is naturally the case for some participants. It can also happen as participants get older, when the glandular tissue in one breast decreases slightly more than in the other.
     
• Examples of a benign architectural distortion:
  • previous surgery or past breast infection may change the shape of the glandular tissue;
  • sometimes the breast is positioned slightly differently when the image is taken, compared to the other images. This can make it appear that there is an architectural distortion when there is not.

What happens if the radiologists are not sure?

Sometimes the radiologists cannot clearly determine whether something is different from normal. The medical term for this result is BI-RADS 0. The radiologists will then refer a participant to the hospital for further examination. This may include an additional X-ray or an ultrasound scan. Of every 10 participants with this result who undergo further testing, 9 do not have breast cancer.