Breast cancer is the most common cancer diagnosed in women in the United States, and screening has been one of the tools linked to a large decline in breast cancer deaths over the past few decades. A mammogram is a low-dose X-ray exam of the breast used to find cancers when they are small and most treatable. The 2024 US Preventive Services Task Force (USPSTF) guidelines recommend biennial screening starting at age 40 for average-risk women — an update from earlier guidance that left the 40s to individual choice. Understanding the difference between screening and diagnostic mammograms, what BI-RADS scores mean, and when supplemental imaging is appropriate helps you take part in the decisions. This article is general education, not medical advice; when to start, how often to screen, and which tests are right for you are decisions to make with a clinician who knows your history.
What a Mammogram Is and Who Should Get One
A mammogram uses low-dose X-rays to image the breast tissue, typically capturing a craniocaudal (top-down) and a mediolateral oblique (angled side) view of each breast. According to the US Preventive Services Task Force (USPSTF), the 2024 recommendation is biennial screening mammography for women aged 40 to 74 who are at average risk (a Grade B recommendation).
The 2024 update strengthened the guidance for women in their 40s: rather than framing screening before 50 as an individual decision, the Task Force now recommends that average-risk women begin at 40. Other organizations go further. The American College of Radiology (ACR) and Society of Breast Imaging recommend annual screening starting at age 40 for average-risk women, and they advise that all women have a formal risk assessment by around age 25 — earlier for those at higher risk. The American Cancer Society (ACS) offers a tiered approach: women aged 40 to 44 have the option to start annual screening, women 45 to 54 should screen annually, and women 55 and older can switch to every other year or continue annually, as long as they are in good health with a life expectancy of at least 10 years.
Higher-risk women — those with a strong family history, known BRCA1/BRCA2 or other high-risk gene mutations, or a history of chest radiation in youth — typically begin earlier and may add breast MRI screening, per National Cancer Institute and specialty guidance. For women 75 and older, the USPSTF found the evidence insufficient to make a general recommendation, so the decision is individualized based on overall health. Because the major organizations differ, your own clinician personalizes the plan to your age, risk, and preferences.
Screening vs Diagnostic Mammograms
The two main types of mammograms differ in purpose, and the distinction matters for both interpretation and cost. A screening mammogram is performed on someone without breast symptoms to look for early cancers. The exam is brief, follows a standardized protocol, and is often interpreted by the radiologist in batches, with results usually available within a day or two.
A diagnostic mammogram is performed when there is a specific concern: a palpable lump, nipple discharge, focal pain, skin changes, or an abnormality flagged on a prior screening exam. Diagnostic mammograms include additional or specialized views, are often combined with breast ultrasound, and the radiologist usually reviews the images in real time and may discuss preliminary findings before you leave. Diagnostic exams are frequently billed differently from screening exams, which is worth knowing before your visit.
3D Mammography (Tomosynthesis)
Most modern centers now offer digital breast tomosynthesis (DBT, or 3D mammography), in which the X-ray tube moves in an arc over the breast to acquire multiple low-dose images that are reconstructed into thin slices. Studies have reported that DBT can improve cancer detection and reduce recall (call-back) rates compared with traditional 2D mammography, with the benefit often most noticeable in women with dense breasts. Coverage for 3D mammography has become widespread, though whether it is offered — and how it is billed — can still vary by center and plan, so it is reasonable to ask when you schedule.
What to Expect During the Exam
The exam typically takes about 15 to 20 minutes. You undress from the waist up and put on a gown. The technologist positions each breast on a flat plate, and a second plate slowly compresses the tissue from above. Compression flattens the breast to reduce tissue overlap and motion, which lowers the radiation dose needed and improves image quality. Compression lasts only a few seconds per view.
Most people describe compression as uncomfortable but not painful, and discomfort is often less in the week after a menstrual period, when breasts tend to be less tender. You can ask the technologist to ease pressure if it becomes painful. The National Cancer Institute suggests scheduling around cyclical breast tenderness when possible and avoiding deodorant, lotion, and powder on exam day, because residue can create spots on the image that mimic abnormalities.
Reading Results: BI-RADS Scoring
Results are reported using the Breast Imaging Reporting and Data System (BI-RADS), a standardized scoring system developed by the American College of Radiology:
- BI-RADS 0: Incomplete — additional imaging (or comparison with prior images) is needed.
- BI-RADS 1: Negative — no findings; resume routine screening.
- BI-RADS 2: Benign finding — resume routine screening.
- BI-RADS 3: Probably benign — short-interval (usually 6-month) follow-up; a low chance of cancer (generally cited as 2 percent or less).
- BI-RADS 4: Suspicious — biopsy is generally recommended; this category spans a wide range of cancer probability.
- BI-RADS 5: Highly suggestive of malignancy — biopsy is recommended.
- BI-RADS 6: Known biopsy-proven cancer.
Roughly 1 in 10 screening mammograms results in a recall (BI-RADS 0) for additional views, and most recalls turn out to be benign. Only a small share of screening mammograms ultimately lead to a cancer diagnosis. A recall is common and is not the same as a cancer diagnosis — it usually just means the radiologist wants a clearer look.
Dense Breasts and the FDA Notification Rule
Since September 10, 2024, the FDA’s updated Mammography Quality Standards Act (MQSA) regulations require mammogram reports nationwide to include a breast-density notification. Under the rule, your results letter must state whether your breasts are “dense” or “not dense” and explain, in standardized language, that dense tissue can make it harder to find cancer on a mammogram and is itself associated with a somewhat higher risk of breast cancer.
Dense breasts are common — a large share of women aged 40 to 74 have dense breast tissue — and having dense breasts is normal, not a disease. The practical point is that dense tissue and tumors can both appear white on a mammogram, which can lower the sensitivity of the exam. Density is one factor, alongside your overall risk, that you and your clinician can use to decide whether supplemental screening makes sense for you.
Limitations and Supplemental Screening
Mammography is highly valuable but not perfect. Its sensitivity is generally lower in women with dense breasts, which is why the density notification exists. For women with dense breasts or elevated risk, supplemental screening with breast ultrasound or breast MRI can sometimes find cancers not seen on mammography. Annual MRI screening (in addition to mammography) is generally recommended for women at high lifetime risk — for example, those with a lifetime breast cancer risk of about 20 percent or more, known high-risk gene mutations, or a history of chest radiation. The USPSTF has said the current evidence is insufficient to recommend for or against supplemental screening specifically because of dense breasts, so this remains an individualized decision. Insurance coverage for supplemental screening varies by state and plan, so verify current rules before scheduling.
When results require prompt follow-up: A suspicious mammogram (BI-RADS 4 or 5) calls for timely evaluation and, usually, a biopsy. If you notice a new breast lump, nipple discharge, skin dimpling or thickening, or unexplained focal pain between screenings, contact your provider promptly rather than waiting for the next scheduled mammogram. A normal recent mammogram does not rule out a new, symptomatic finding.
Cost Considerations
Under the Affordable Care Act, most private plans and Medicare cover screening mammograms for women 40 and older with no out-of-pocket cost when you use an in-network provider, and many plans include 3D screening at no cost-sharing. Diagnostic mammograms — those done to evaluate symptoms or a recall — are typically subject to your deductible and coinsurance, although a growing number of states have passed laws requiring diagnostic breast imaging to be covered like screening. Without insurance, screening mammograms commonly cost roughly $100 to $300 and diagnostic mammograms more, though prices vary widely by region and facility, so treat these as general estimates and confirm the cash price in advance.
Cost should rarely be a barrier to a needed mammogram. The CDC’s National Breast and Cervical Cancer Early Detection Program (NBCCEDP) offers free or low-cost screening to eligible uninsured and underinsured women, and many community programs and imaging centers run their own assistance programs. Our healthcare costs guide covers how to access these resources, and the medical conditions resource library covers cancer screening more broadly. If getting to a center is difficult, a telehealth visit can be a convenient way to discuss your risk and get a referral, even though the mammogram itself must be done in person.
Frequently Asked Questions
How often should I get a mammogram?
The 2024 USPSTF recommendation is every 2 years from age 40 to 74 for average-risk women. The ACR recommends annual screening from 40 onward, and the ACS supports annual screening at 45 to 54 with the option to start at 40 and to move to every other year at 55. Higher-risk women may need to start earlier and screen more often. Discussing your specific risk profile with your clinician is the practical way to settle on a schedule.
What if I have dense breasts?
Dense breasts are common and normal, but they reduce a mammogram’s sensitivity and slightly raise risk. Since September 2024, your report must tell you whether your breasts are dense. Depending on your overall risk, your clinician may suggest 3D mammography, supplemental ultrasound, or MRI. This is a personalized decision, not a one-size-fits-all rule.
Does a mammogram use a lot of radiation?
The radiation dose from a standard mammogram is low — on the order of a fraction of a millisievert, comparable to a few weeks of natural background radiation. 3D mammography can add a small amount of dose, though newer systems can generate synthetic 2D images to limit it. For women in screening age ranges, the cancer-detection benefit is generally considered to far outweigh the small theoretical radiation risk.
What happens if my mammogram is abnormal?
Most abnormal screening mammograms turn out to be benign. The usual next step is a diagnostic mammogram with additional views, often combined with ultrasound. If the radiologist remains concerned, an image-guided breast biopsy is the next step. Many biopsies show benign findings, so a recommendation for further testing is not the same as a cancer diagnosis.
Are screening mammograms really free?
For most insured women 40 and older, in-network screening mammograms are covered with no cost-sharing under the ACA, and Medicare covers annual screening. Diagnostic mammograms may involve out-of-pocket costs unless your state requires otherwise. Coverage rules change, so verify with your plan.
The Bottom Line
A mammogram is among the most studied cancer-screening tests in modern medicine, with a substantial mortality benefit when done regularly. Useful conversations with your provider include when to start based on your personal and family history, whether 3D mammography is offered at your center, what your breast density means for supplemental screening, and how to keep follow-up consistent if you change insurance or move. Staying with the same imaging center when you can allows year-over-year comparison, which is one of the most valuable features of mammographic screening. Above all, the right screening plan is the one you and your clinician build around your individual risk.
Medical disclaimer: This article is general education, not medical advice, and it is not a substitute for care from a qualified clinician. Screening recommendations, coverage rules, and prices change and vary by organization, state, and insurance plan — the figures here are general estimates. When to start screening, how often, and whether to add tests such as ultrasound or MRI are individualized decisions to make with your own clinician, who knows your risk and history. If you notice a new breast lump, nipple discharge, or other worrying change, contact your provider promptly; for a medical emergency, call 911. Verify current guidelines and benefits before acting.
Sources
- U.S. Preventive Services Task Force (USPSTF) — Breast Cancer: Screening (2024 final recommendation)
- American Cancer Society (ACS) — Breast cancer screening guidelines and recommendations
- American College of Radiology (ACR) and Society of Breast Imaging (SBI) — Breast cancer screening recommendations
- National Cancer Institute (NCI) — Mammograms fact sheet; Breast cancer overview
- U.S. Food and Drug Administration (FDA) — Mammography Quality Standards Act (MQSA) breast density reporting rule (effective September 10, 2024)
- Centers for Disease Control and Prevention (CDC) — National Breast and Cervical Cancer Early Detection Program (NBCCEDP)
- HealthCare.gov — Preventive care benefits for women