Mammogram Screening: When to Start and What to Expect

What a screening mammogram does

A mammogram is a low-dose x-ray of the breast. Screening mammography looks for breast cancer before a person has symptoms. The Centers for Disease Control and Prevention (CDC) explains that mammograms can find cancer before it is large enough to feel or cause symptoms and are the best screening method for most people of screening age.

Screening does not prevent breast cancer, and no screening test finds every cancer. It can also lead to a callback for more images or testing when cancer is not present. The goal is to balance earlier detection with possible harms such as false-positive results, additional procedures, anxiety, radiation exposure, and overdiagnosis.

Current mammogram screening age guidance

The USPSTF's April 30, 2024 final recommendation calls for mammography every two years from ages 40 through 74 for average-risk women and other people assigned female at birth. The Task Force found insufficient evidence to determine the balance of benefits and harms for screening at age 75 and older, so that decision should be individualized.

The recommendation includes people at average risk and some who have factors such as a first-degree family history or dense breasts. It does not apply to people with a known high-risk genetic marker such as BRCA1 or BRCA2, previous high-dose chest radiation at a young age, previous breast cancer, or a high-risk lesion found on biopsy. Those situations may require earlier, more frequent, or different imaging based on specialist guidance.

Symptoms are not routine screening

Do not wait for the next scheduled screening if you notice a new breast or underarm lump, thickening, swelling, skin dimpling, nipple changes, discharge other than breast milk, a change in breast shape, or persistent breast pain. The CDC lists these as symptoms that deserve medical attention.

A clinician may recommend diagnostic imaging rather than routine screening when a symptom or prior abnormal finding is present. An urgent evaluation does not necessarily mean cancer; it means the concern needs the right type of assessment.

What happens during a mammogram

At the imaging facility, a technologist positions one breast on a flat plate. A second plate presses the breast firmly to spread the tissue and hold it still while images are taken. The breast is repositioned for another view, and the process is repeated on the other side. The CDC notes that patients can expect pressure during compression.

Compression is brief and helps produce a clearer image with less motion. Some people experience discomfort. Tell the technologist if you are in pain, have limited shoulder movement, use a mobility aid, have breast implants, are pregnant or may be pregnant, or need another accommodation. The imaging team can explain what adjustments are possible without compromising the exam.

How to prepare for the appointment

1. Confirm the type of appointment. Tell the facility about symptoms, prior abnormal results, implants, or breast surgery so it can determine whether screening or diagnostic imaging is appropriate.
2. Bring prior imaging information. If earlier mammograms were done elsewhere, ask how to transfer the images and reports for comparison.
3. Follow the facility's clothing and product instructions. Many facilities advise avoiding deodorant, powder, lotion, or perfume on the breasts and underarms that day because particles can appear on images.
4. Ask about comfort. If breasts tend to be tender at certain times, ask whether timing the visit differently is reasonable. Do not delay a clinically important evaluation without professional guidance.
5. Plan for results and costs. Confirm where the report will be sent, how callbacks are handled, insurance or self-pay charges, and whether additional imaging would be billed separately.

Understanding breast-density information

Breast density is a finding on mammography, not something a person can determine by touch. Dense breasts have more fibrous and glandular tissue relative to fatty tissue. Density can make abnormalities harder to see on a mammogram and is also associated with a higher risk of breast cancer.

Since September 10, 2024, facilities covered by the federal Mammography Quality Standards Act must include breast-density information in the patient summary. The U.S. Food and Drug Administration (FDA) advises patients with dense breasts to discuss density, personal risk, and individual circumstances with a healthcare professional.

A dense-breast result does not automatically mean that ultrasound or MRI is right for everyone. The USPSTF found insufficient evidence to recommend for or against supplemental ultrasound or MRI after an otherwise negative mammogram based on density alone. Ask what the report means in the context of your complete risk history.

What happens after the images are taken

A qualified interpreting physician reviews the images and sends a report. The patient also receives a summary in understandable language. Results may be negative, may recommend routine future screening, or may request comparison, additional views, ultrasound, or another evaluation.

A callback is not a cancer diagnosis. Still, recommended follow-up should not be ignored. Ask what test is needed, how soon to complete it, who will explain the result, and what happens next. Keep copies of reports and note the recommended screening or follow-up date.

Questions to discuss during primary care

• Does the average-risk screening recommendation apply to me?
• Does my family history suggest formal risk assessment or genetic counseling?
• Do prior biopsies, chest radiation, breast cancer, or other findings change my plan?
• What did my breast-density result mean, and is any additional evaluation appropriate?
• Who will order the mammogram and receive the report?
• How will we track the next due date and make sure an abnormal result is completed?

For broader visit planning, see Cityworld Health's adult preventive-care checklist and guide to preparing for primary-care follow-up.