What is a screening mammogram ?

There is a difference between a screening mammogram and a diagnostic mammogram.

  • A screening mammogram is the routine mammogram that you are asked to have every two years, even though there are no symptoms, upon screening invitation letter
  • A diagnostic mammogram is one that is prompted by the appearance of a sign or symptom in the breast. This symptom requires an exploration by mammography, among other imaging techniques, in order to identify and diagnose the problem in the breast.

What are the major signs that should lead you to consult?

  • Modification of the roundness, of the general shape of the breast (irregularities, distortions).
  • Retraction of the nipple
  • Recent lump or swelling, especially if there is little mobility when palpated.
  • Flat, i.e. the flatter area of the breast, which disrupt the roundness of the breast.
  • Bloody discharge
  • Unexplained redness
  • Lump in the armpit, persistent or increasing in volume
  • “Orange peel” with the appearance in the affected area of “pads”, small blisters perceptible between two fingers.
  • Wound on the skin, due to ulcerative cancer
  • Swelling and firmness of the entire breast
  • Deeply palpable mass, occurring without visible external deformation
    Beware, not all of these signs are typical of cancer; they can also be indicative of benign breast disease! Nevertheless, they should motivate you to consult a doctor.

Screening mammography is not a prevention method.

Preventing a disease means doing everything possible to ensure that it does not occur. For example, avoiding smoking is a good preventive attitude towards lung cancer.

Screening is searching for a disease in a person who has no symptoms, and who does not complain about anything at all. Repeating mammograms can in no way prevent breast cancer. The mammographic image restitutes what is already present in the organ.

How does a mammography screening take place in France ?

In practice, the woman notified to attend makes an appointment at the radiology office of her choice. She will have a mammography exam followed by an ultrasound examination depending on necessity (dense breasts or radiological abnormality to be clarified). These images will be interpreted by the radiologist, who is the “first reader” of the examination. He will make a report and propose a classification of the examination (see below). This file (images and report of the first reader) is sent to the departmental structure in charge of managing the screening depending on the patient residence. The images will be reviewed there by another radiologist, the “second reader” , coming from another radiology office or medical imaging structure, and who does not know the woman patient. He will establish his verdict without having seen or questioned her, only on the available images. He will ‘report’ his verdict in the form of a classification, either in concordance with the first radiologist reader or, on the contrary, in discordance, which will imply a call back of the woman patient for further exploration.
Mammography classification is a radiological classification, depending on the greater or lesser degree of certainty that the imagery pleads in favour of a cancerous lesion. It is by no means a prognostic classification. The ACR (American College of Radiology) classification was developed in 1990. There are 5 stages.

ACR 1: normal, the breast is “nothing to report”.
ACR 2: images which are just benign abnormalities, such as small axillary ganglions, micro cysts, benign calcifications, images which are not always known what they are but which have remained unchanged for ages, amorphous fibro-adenomas, or cysts which are already well known.
ACR 3: an image which is not worrying but whose outcome are wished to be checked, which has not been known before, or which was been known but has changed slightly compared to previous evaluations. The proposed conduct is a single monitoring at 4 or 6 months, depending on whether masses or calcifications are involved, and then eventually at one year.
ACR 4 means that there is a high probability of cancer, and in any case a suspicious anomaly, to be further investigated. ACR4 therefore automatically implies a biopsy, under ultrasound (micro-biopsy) or under radiographic control, by a mammotome procedure (macro-biopsy), or directly by biopsy-exeresis.
ACR 5: the anomaly is very strongly suspected of malignancy and the semiological criteria are quite representative and typical of malignancy.
ACR 0 designates an incomplete examination to which other imaging examinations must be associated.

For more explanations and details read here: https://cancer-rose.fr/en/2020/12/30/arc-classification/
Below is a diagram that illustrates the possible situations during a mammography screening.

Click to enlarge

You can see the so-called “false alarm” situation. This is the suspicion of cancer, on a mammographic image, but which will not be confirmed after further examinations. These additional examinations are sometimes heavy, and sometimes even result in biopsies, the number of which has greatly increased since the screening in place, this situation being favoured by the double reading. Experiencing a false alarm is often very stressful, as the woman has to wait sometimes several days or even weeks for confirmation of the absence of disease. For every 1,000 women over the age of 50 participating in screening for 20 years, there are an estimated 1,000 false alarms in France, leading to 150 to 200 unnecessary biopsies (Revue Prescrire, February 2015/Tome 35 N°376).

This is, along with overdiagnosis and radiotoxicity, the third harmful effect of mammographic screening.

False alarm and overdiagnosis aren’t the same thing, don’t confuse both !

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