Mammogram Every Year or Every Two Years? ACS vs USPSTF Explained

"Should you get a mammogram every year or every two years? U.S. guidelines differ based on age, risk, and screening recommendations."

Illustration. A doctor explains cancer examination and treatment to a patient at a hospital.

The American Cancer Society (ACS) and the U.S. Preventive Services Task Force (USPSTF) both recommend mammography for women in their 40s and beyond, but they differ on how often average-risk women should be screened.

The ACS recommends annual mammography for women ages 45 to 54, while the USPSTF recommends mammography every two years for women ages 40 through 74.

Neither organization recommends that every woman follow the exact same schedule regardless of her circumstances.

Understanding the difference can help you have a more informed discussion with your healthcare provider.

Medical information: This article is for educational purposes only. Your recommended screening schedule may differ because of your personal and family history, genetic risk, previous breast cancer, symptoms, breast density, or other medical factors.

The Short Answer

For women at average risk:

• ACS: annual mammography is recommended from ages 45–54; beginning at 40 is an option, and women 55 and older can continue annually or switch to every two years.

• USPSTF: mammography every two years from ages 40–74.

The difference is therefore not whether mammography is useful.

The main disagreement is how frequently average-risk women should be screened.

What Does the American Cancer Society Recommend?

The ACS uses an age-based approach that places greater emphasis on annual screening during the 40s and early 50s.

Ages 40–44

Women should have the option to begin annual mammograms.

The ACS does not describe annual mammography in this age group as a universal requirement.

Ages 45–54

The ACS recommends annual mammography.

Age 55 and older

Women can:

• continue annual mammography; or

• switch to mammography every two years.

The ACS recommends continuing screening while a woman remains in good health and has a life expectancy of at least 10 years. (cancer.org)

What Does the USPSTF Recommend?

The USPSTF takes a simpler approach for average-risk women.

Its recommendation is:

Women ages 40 through 74 should receive screening mammography every two years.

The USPSTF gives this recommendation a Grade B, indicating that it believes there is a moderate net benefit from biennial screening for women in this age group. (uspreventiveservicestaskforce.org)

For women age 75 and older, the USPSTF currently says there is insufficient evidence to determine the balance of benefits and harms of screening mammography. (uspreventiveservicestaskforce.org)

Why Do the Guidelines Differ?

At first glance, the difference can seem confusing.

If both organizations review scientific evidence, why don't they recommend the same screening interval?

The reason is that screening involves both benefits and potential harms.

A mammogram can detect breast cancer early.

But screening can also result in:

• false-positive findings;

• additional imaging;

• biopsies;

• anxiety;

• overdiagnosis;

• and treatment of cancers that might not otherwise have caused harm.

Different guideline organizations can weigh these outcomes differently.

The ACS places more emphasis on annual screening during ages when breast cancer becomes more common.

The USPSTF places greater emphasis on balancing the benefits of earlier detection against the potential harms associated with more frequent screening.

Neither organization is saying that mammography is ineffective.

Annual vs. Every Two Years: What's the Difference?

The simplest way to understand the debate is to look at what happens when screening is performed more frequently.

Annual mammography

A woman has a mammogram approximately every 12 months.

Potential advantages include more frequent opportunities to detect a cancer between screening visits.

Potential disadvantages include more screening examinations and potentially more false-positive results and follow-up procedures over time.

Biennial mammography

A woman has a mammogram approximately every 24 months.

Potential advantages include fewer screening examinations and potentially fewer false-positive findings and follow-up procedures.

The tradeoff is that a cancer could develop or become detectable between scheduled screening examinations.

The best interval depends on how an individual patient and clinician weigh these considerations.

Which Schedule Is Better?

There is no single answer that applies to every woman.

For an average-risk woman, both annual and biennial screening can be consistent with major U.S. recommendations depending on age and the guideline being followed.

The more useful question is:

Which screening schedule provides the most appropriate balance of benefit and harm for me?

Factors that can influence the discussion include:

• age;

• personal history;

• family history;

• genetic risk;

• previous breast biopsy;

• breast density;

• prior radiation exposure;

• previous breast cancer;

• overall health;

• and personal preferences.

What If You Are 40 to 44?

This age group is particularly important because the recommendations differ.

Under ACS guidance, women ages 40–44 have the option to begin annual mammography.

Under USPSTF guidance, women ages 40–74 are recommended to have mammography every two years.

Therefore, a 40-year-old woman at average risk could reasonably encounter either of these approaches depending on the healthcare system and clinician following the guideline.

That does not mean one approach is automatically unsafe.

It means the patient should understand which recommendation her clinician is using and why.

What If You Are 45 to 54?

This is where the difference becomes especially clear.

The ACS recommends annual mammography for women ages 45–54.

The USPSTF recommends every-two-year mammography for women ages 40–74.

A woman in her late 40s or early 50s may therefore receive different recommendations from different healthcare professionals.

If that happens, ask:

"Which guideline are you following, and why is that interval appropriate for my risk?"

That question can produce a more useful conversation than simply asking whether annual screening is "right" or "wrong."

What If You Are 55 to 74?

The ACS allows women age 55 and older to continue annual mammography or switch to every-other-year screening.

The USPSTF recommends every-two-year screening through age 74.

For many women, this means there is more flexibility in choosing the interval.

Personal risk and preferences can become particularly important.

Does Family History Change the Recommendation?

Yes, it can.

The ACS and USPSTF recommendations discussed above are primarily intended for women at average risk.

A woman with a strong family history may have a substantially higher lifetime risk than the average population.

For example, risk assessment may consider:

• a mother or sister with breast cancer;

• multiple relatives with breast cancer;

• breast cancer occurring at a young age in the family;

• ovarian cancer in close relatives;

• known hereditary cancer mutations.

High-risk patients may need additional imaging, including MRI, rather than simply choosing between annual and biennial mammography.

The ACS recommends annual MRI plus mammography for certain women with a lifetime breast cancer risk of approximately 20%–25% or greater based on appropriate risk assessment tools. (cancer.org)

Does Breast Density Change How Often You Need a Mammogram?

Not necessarily.

Dense breast tissue can make some cancers more difficult to detect on mammography.

However, breast density alone does not automatically mean that a woman should receive mammography more frequently.

The USPSTF currently finds insufficient evidence to determine whether supplemental ultrasound or MRI provides a net benefit after a negative mammogram in women with dense breasts. (uspreventiveservicestaskforce.org)

The decision should be individualized.

If you have dense breasts, ask your clinician whether your overall risk warrants supplemental imaging.

What About Women Over 74?

The evidence becomes less certain as women get older.

The USPSTF currently says there is insufficient evidence to assess the benefits and harms of screening mammography in women age 75 and older. (uspreventiveservicestaskforce.org)

The ACS takes a somewhat different approach and recommends continuing screening as long as a woman remains in good health and is expected to live at least another 10 years. (cancer.org)

For older adults, the decision should therefore take into account:

• overall health;

• life expectancy;

• other medical conditions;

• previous screening results;

• breast cancer risk;

• and personal preferences.

Is Annual Mammography More Expensive?

Potentially, because a patient is receiving twice as many screening examinations over a given period.

However, the amount a patient actually pays depends on insurance coverage.

For many eligible preventive services covered under applicable federal requirements, cost-sharing may be waived when the service meets the relevant preventive-care rules and is performed by an in-network provider.

But diagnostic imaging is different.

For example:

Routine screening mammogram

is not necessarily processed the same way as:

Diagnostic mammogram after an abnormal result.

Patients should check their individual health plan.

Does Medicare Pay for Annual Mammograms?

Medicare covers eligible breast cancer screening services, but patients should distinguish between screening and diagnostic care.

The cost and coverage rules can depend on the type of service, eligibility and whether the provider accepts Medicare assignment.

Medicare Advantage plans can also have network and plan-specific requirements.

Before scheduling a test, Medicare beneficiaries can ask:

"Is this being billed as a preventive screening mammogram or a diagnostic mammogram?"

That distinction can matter when determining patient cost-sharing.

Can a Mammogram Be Done Every Year If My Doctor Recommends It?

Yes.

A patient and clinician may decide that annual screening is appropriate based on the patient's age, risk factors and preferences.

The existence of the USPSTF biennial recommendation does not mean that annual mammography is prohibited.

Likewise, following a two-year schedule consistent with USPSTF guidance does not mean a woman is refusing appropriate cancer screening.

The key is to understand the recommendation being used and why.

What If I Missed Several Years of Mammograms?

Do not assume you need to "make up" every missed screening appointment.

Instead, contact your healthcare provider and discuss your current situation.

Your clinician can determine whether you should receive a routine screening mammogram or whether another type of evaluation is appropriate.

If you currently have symptoms, the appropriate examination may be diagnostic rather than screening.

What If My Mammogram Is Abnormal?

An abnormal screening mammogram does not automatically mean breast cancer.

Additional evaluation may include:

• diagnostic mammography;

• ultrasound;

• MRI in selected circumstances;

• or biopsy.

The next step depends on the specific imaging finding.

Patients should follow up promptly rather than assuming that an abnormal screening result is a cancer diagnosis.

Annual vs. Biennial Mammography: Quick Comparison

This table is a simplified comparison and should not be used to determine an individual's medical care.

Questions to Ask Your Healthcare Provider

If you are unsure whether you should have annual or biennial mammography, ask:

1. Am I considered average risk?

2. Which breast cancer screening guideline are you following?

3. Why do you recommend this interval for me?

4. Does my family history change my risk?

5. Should I have a formal breast cancer risk assessment?

6. Do I have dense breasts?

7. Would I benefit from supplemental MRI or ultrasound?

8. What happens if my mammogram is abnormal?

9. Will the screening be covered by my insurance?

10. Will additional diagnostic imaging have different cost-sharing?

The Bottom Line

The debate over annual versus biennial mammography is not a disagreement about whether breast cancer screening matters.

It is a difference in how major medical organizations balance the benefits of earlier detection against the potential harms of more frequent screening.

For women at average risk:

• ACS: annual mammography is recommended from ages 45–54, with the option to begin at 40 and the option to move to every two years at 55.

• USPSTF: mammography every two years from ages 40–74.

For women with significant risk factors, neither schedule should automatically be assumed to apply.

If you are unsure which schedule is appropriate, ask your healthcare provider:

"Based on my age, family history and overall breast cancer risk, should I have a mammogram every year or every two years—and why?"

That conversation is more important than choosing a schedule based solely on a general rule.

Medical Sources

This article was fact-checked against:

• American Cancer Society

• U.S. Preventive Services Task Force

• Centers for Disease Control and Prevention

• National Cancer Institute

• Medicare.gov

Last reviewed for source accuracy: October 2026.

Medical disclaimer: This article is for general educational purposes only and is not a substitute for professional medical advice, diagnosis or treatment.