Mammogram: purpose, procedure and what changes with age
In brief
A mammogram is a low-dose X-ray of the breasts that can detect breast cancer before it can be felt. In France, it is offered every 2 years between 50 and 74 as part of the organised screening programme, together with a clinical breast examination and a second reading of the images, and is fully covered on invitation; outside this programme, it is used to investigate a symptom or to monitor women at higher risk. The test takes about 15 to 20 minutes and usually involves two images of each breast.
What is a mammogram used for?
Mammography is the main breast imaging test. It picks up abnormalities that may be invisible and impossible to feel: small lumps, distortions of the breast tissue and above all microcalcifications, tiny calcium deposits that can be the first sign of an early cancer. It has two distinct uses:
- Screening mammogram: in a woman with no symptoms, to detect cancer at an early stage.
- Diagnostic mammogram: to investigate a symptom (lump, nipple discharge, inverted nipple) or monitor a known abnormality.
It is part of the prevention and care pathway in gynaecological cancer care. For the signs of breast cancer and its treatment, see our article on breast cancer.
At what age should you have a mammogram?
How often depends on your age and your level of risk:
| Situation | Recommendation in France |
|---|---|
| Under 50, no symptoms or particular risk | No routine mammogram; a breast examination by a health professional once a year from age 25 |
| 50 to 74, average risk | National screening programme: mammogram and breast examination every 2 years, fully covered by the Assurance maladie (national health insurance) |
| Over 74 | Individual decision with your doctor, depending on your health |
| High risk (family history, personal history of cancer or atypical lesion) | Specific follow-up, sometimes before 50, set by your doctor according to guidelines from the French National Authority for Health (HAS) |
| BRCA1 or BRCA2 mutation | Yearly breast MRI and mammogram from age 30, within a cancer genetics programme |
| A symptom, at any age | Diagnostic mammogram (under 30, ultrasound is the first test) |
The International Agency for Research on Cancer (IARC) has concluded that mammography reduces deaths from breast cancer in women aged 50 to 74. Screening also has drawbacks, such as overdiagnosis of cancers that would never have progressed: these are explained in the invitation letter and can be discussed with your doctor.
What happens during a mammogram?
- You undress to the waist. The radiographer positions one breast at a time on the machine.
- A plate compresses the breast for a few seconds. This spreads out the tissue, sharpens the images and lowers the radiation dose. It can be uncomfortable, rarely painful; let the radiographer know if it hurts.
- Two images of each breast are usually taken: one from above (craniocaudal view) and one at an angle (oblique view), which also shows the breast tissue extending towards the armpit. Extra images (side view, magnification, spot compression) are added if an area needs a closer look.
- The radiologist often adds an ultrasound scan, particularly if the breasts are dense, and performs a breast examination as part of the screening programme.
The test takes about 15 to 20 minutes. The radiation dose is low.
How should I prepare for a mammogram?
- Do not apply deodorant, talc or cream to your breasts and armpits on the day: some products create images that look like calcifications.
- Bring your previous mammograms and reports: comparison is essential.
- Mention breast implants, previous surgery or biopsy, possible pregnancy or breastfeeding.
When in my cycle should I have a mammogram before the menopause?
Before the menopause, breast tissue is more abundant and more sensitive to hormones. The breasts are denser, which makes the images a little harder to read, and compression can be more uncomfortable towards the end of the cycle.
It is advisable to book your mammogram in the first half of your cycle, ideally between day 7 and day 14 after the start of your period. To understand these phases better, see our article on the menstrual cycle.
During pregnancy and breastfeeding, ultrasound is the first-line test; a mammogram remains possible if needed.
Why is a mammogram more accurate after the menopause?
After the menopause, breast tissue gradually shrinks and is replaced by fat. On the images, fat appears dark while breast tissue appears white, as do tumours: an abnormality therefore stands out better in a fatty breast. This is one reason why mammography works particularly well at this age, which is also when the risk of breast cancer is highest.
Menopausal hormone therapy can maintain or increase breast density. Let the radiologist know if you take it. See our article on menopause hormone therapy.
What does dense breast tissue mean on a mammogram?
The report states the density of your breasts, graded into four types:
- Type A: breasts almost entirely fatty;
- Type B: scattered areas of fibroglandular density;
- Type C: heterogeneously dense breasts, which may hide small lesions;
- Type D: extremely dense breasts, which reduce the sensitivity of mammography.
Dense breasts are common, especially in younger women, and are not a disease. But high density moderately increases the risk of cancer and makes mammography less accurate. An additional ultrasound is then often performed. The European Society of Breast Imaging (EUSOBI) recommends informing women of their breast density and suggests, for extremely dense breasts between 50 and 70, a screening MRI every 2 to 4 years; this recommendation is not currently part of the French screening programme, and the decision is made with your doctor.
How do I read my mammogram result (BI-RADS)?
The radiologist concludes with an ACR (BI-RADS) category:
| Category | Meaning | Usual next step |
|---|---|---|
| ACR 0 | Incomplete assessment | Additional images or ultrasound, comparison with previous tests |
| ACR 1 | Normal | Usual screening interval |
| ACR 2 | Benign finding | Usual screening interval |
| ACR 3 | Probably benign finding | Short-interval follow-up, usually at 6 months |
| ACR 4 | Suspicious finding | Biopsy |
| ACR 5 | Finding highly suggestive of cancer | Prompt biopsy |
In the French screening programme, every mammogram judged normal or benign is reviewed by a second expert radiologist. You receive the final result after this second reading. Being recalled for further tests does not mean you have cancer: the vast majority of these findings turn out to be benign. If a lump is found, see our article breast lump: what should I do?
Frequently asked questions
Does a mammogram hurt?
Compression is often uncomfortable but brief, a few seconds per image. Before the menopause, having it in the first half of your cycle makes it easier to tolerate.
Can I have a mammogram with breast implants?
Yes. Tell the imaging centre: adapted views are taken so that the breast tissue in front of the implant can be properly assessed.
Is the radiation from a mammogram dangerous?
The dose is low. For women aged 50 to 74, the benefit of screening is considered to clearly outweigh this very small risk.
What if I have not received an invitation for breast screening?
In France, you can ask your doctor or gynaecologist, who can prescribe the test, or contact the regional cancer screening coordination centre for your area.
Do I need an ultrasound as well as a mammogram?
Not routinely. The radiologist adds one if your breasts are dense, if you have a symptom, or to characterise something seen on the mammogram.
Is a mammogram reimbursed?
In the organised screening programme, from 50 to 74, the mammogram and clinical examination are fully covered when you present your invitation. Outside this programme, a mammogram prescribed by a doctor is reimbursed by the Assurance maladie (French national health insurance) on the usual terms.
References
- Haute Autorité de santé (HAS). Dépistage du cancer du sein en France : identification des femmes à haut risque et modalités de dépistage. Saint-Denis : HAS, 2014. has-sante.fr
- Lauby-Secretan B, et al. Breast-cancer screening--viewpoint of the IARC Working Group. New England Journal of Medicine, 2015. doi:10.1056/NEJMsr1504363 — PMID 26039523
- Mann RM, et al. Breast cancer screening in women with extremely dense breasts recommendations of the European Society of Breast Imaging (EUSOBI). European Radiology, 2022. doi:10.1007/s00330-022-08617-6 — PMID 35258677
Dr Olivier KadochObstetrician-gynaecologist and gynaecological surgeon in Paris (16th and 5th arrondissements). Former chef de clinique-assistant (senior registrar) at the Paris public hospitals (AP-HP); individually accredited by the French National Authority for Health (HAS). RPPS 10003957809. Background and practice locations
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