New guidance from the American College of Physicians (ACP) recommends biennial mammography screening for average-risk women ages 50 to 74. The recommendation aligns with the United States Preventive Services Task Force (USPSTF), but it differs from guidance issued by several specialty organizations that continue to support annual screening beginning at age 40 for many patients.

Lauren Carcas, M.D., a medical oncologist with Baptist Health Herbert Wertheim Cancer Institute, says the ACP recommendation reflects a risk-based approach intended to distinguish patients who may benefit from more intensive screening from those who may safely undergo less frequent imaging. But she cautions that applying biennial screening broadly may have unintended consequences.

“This recommendation assumes that all women have equal access to individualized discussions and nuanced risk assessment through either their primary care or gynecologic physicians,” Dr. Carcas says.

That assumption is clinically important, she adds, because disparities in access to screening, risk assessment and timely treatment already contribute to worse outcomes in some populations. Less frequent screening could further widen those gaps and increase the risk of delayed diagnosis among patients who already face barriers to care.

Ongoing Discordance Among Guidelines

The ACP recommendation now aligns with the USPSTF in supporting biennial mammography for average-risk women ages 50 to 74. However, it remains inconsistent with recommendations from organizations including the National Comprehensive Cancer Network, American Society of Breast Surgeons, American College of Radiology and Society of Breast Imaging, which generally support more frequent screening strategies.

For clinicians, the screening interval remains the central area of disagreement. Dr. Carcas also notes that the ACP guidance recommends against supplemental MRI or ultrasound for dense breast tissue and supports digital breast tomosynthesis, or 3D mammography. Radiology societies, by contrast, strongly support consideration of supplemental ultrasound and/or MRI in selected patients, particularly those with dense breasts or elevated risk.

Balancing False Positives and Missed Cancers

The ACP’s less frequent screening interval is intended in part to reduce false-positive findings and downstream interventions associated with annual screening. However, Dr. Carcas says the evidence base has limitations.

“There has not yet been a randomized controlled trial specifically looking at the mortality difference between annual and biennial screening,” she says.

That evidence gap is especially relevant for patients whose baseline risk is not well captured by age alone. Black women, for example, have higher breast cancer mortality and are more likely to present with aggressive tumor biology at younger ages. Patients with dense breast tissue also have both increased breast cancer risk and higher false-negative rates on mammography.

“These factors should tilt toward more intensive screening,” Dr. Carcas says.

Patients with a significant family history or Ashkenazi Jewish ancestry also warrant careful assessment for hereditary predisposition and may be better served by annual screening and supplemental imaging when indicated.

Risk Assessment Should Begin Early

While guideline groups differ on screening interval, major U.S. societies agree that mammography should be available starting at age 40. Dr. Carcas recommends formal breast cancer risk assessment by age 25 to guide long-term screening strategy.

Patients with a lifetime breast cancer risk greater than 20 percent are considered high risk and should undergo annual screening, with consideration of supplemental breast MRI and ultrasound. For average-risk patients, the decision between annual and biennial mammography should be individualized through shared decision-making, incorporating patient values, breast density, family history, race and ethnicity, genetic risk, prior biopsies and access to follow-up care.

Clinical Implications

For Dr. Carcas, the primary concern is ensuring that simplified screening recommendations do not replace individualized clinical judgment.

Early-stage detection remains associated with less intensive treatment and more favorable outcomes. Patients diagnosed at stage 1 or stage 2 are less likely to require chemotherapy or other aggressive modalities, and successful outcomes are more common.

Dr. Carcas says she plans to continue recommending annual screening for her patients and will offer ultrasound and MRI to those with dense breast tissue or elevated risk.

She also raises a practical concern for clinicians: whether differing recommendations among national organizations could affect insurance coverage for screening and supplemental imaging.

“I remain hopeful this new recommendation from ACP will not alter insurance coverage for patients undergoing screening — particularly in light of the differing recommendations among medical societies,” she says.

Clinical takeaway: The ACP guidance may be appropriate for some average-risk patients, but screening decisions should remain individualized. Formal risk assessment, attention to breast density and recognition of disparities are essential to avoid under-screening patients who may benefit from earlier or more intensive surveillance.