A highly anticipated study reveals that annual mammograms might not always be the optimal method for detecting breast cancer.

Presented at the San Antonio Breast Cancer Symposium, a study led by Dr. Laura Esserman—breast cancer surgeon and director of the University of California, San Francisco Breast Care Center—indicates that personalized screening schedules tailored to a woman’s breast cancer risk can be equally effective at detecting the disease.

Esserman initiated the WISDOM study in 2016 to investigate if personalized risk assessments for breast cancer could yield alternative screening plans that work better than one-size-fits-all annual mammograms. The initial findings, involving over 28,000 women aged 40 to 74, suggest that risk-stratified screening regimens (for both high and low-risk women) are as effective as standard annual mammograms.

All participants (who had no prior breast cancer) were randomly assigned to either personalized risk-based screening or annual mammograms. They were followed for an average of five years to monitor cancer development. In the first analysis, Esserman’s team found that alternative regimens—whether more or less frequent than annual—matched annual screening in detecting breast cancer, meaning no cancers were overlooked with these tailored plans.

The number of Stage 2B breast cancers (a stage where mortality jumps three to eight times) was lower in the personalized screening group than in the annual screening group. “We saw a 33% drop in Stage 2B cases—this is extraordinary,” Esserman noted. “Even I’m stunned by these outcomes.”

The WISDOM study also confirmed that adjusting screening schedules didn’t harm women by missing cancers. “This research is a critical prerequisite for rolling out risk-based screening,” Esserman said. “Our top priority was to prove it’s safe.”

Esserman has long criticized one-size-fits-all breast cancer screening guidelines. She and fellow experts have long recognized that women face vastly different breast cancer risks. For instance, as researchers uncovered more genetic risk factors, they identified multiple mutations linked to increased risk. Additionally, studies show not all breast cancer patients have a family history—yet this has long been a key risk factor doctors used.

The WISDOM study’s risk-based approach included genetic testing for nine breast cancer-related genes. Individually, some of these genes have minimal impact on risk, but combined, research ties them to higher risk. Other factors—breast density, age, personal or family history of breast cancer—were also factored in. Using these data, Esserman’s team created an algorithm to assign women to one of four screening plans: All received risk factor counseling; highest-risk women got alternating mammograms and MRIs every six months; elevated-risk women had annual mammograms; average-risk women got mammograms every two years; lowest-risk women skipped mammograms unless their risk score changed.

Esserman notes that personalized risk assessments enable more targeted screening, which can benefit women. Though the current study focused on safety, she plans to track treatment and outcomes moving forward. “We’re refining our risk prediction and reduction tools to boost breast cancer prevention efforts,” she explained. Current screening methods are too general—they don’t differentiate between high and low-risk women, leading to over-treatment for some and missed cancers for others. “Our goal is to identify those with the highest cancer risk,” she added.

A core component of risk-based screening is a robust algorithm that integrates the latest insights into major breast cancer risk factors—this requires updating long-standing beliefs. Esserman also argues the findings support routine genetic testing for women at younger ages, as many high-risk breast cancers develop in women’s 30s. For example, 30% of study participants with high-risk genes had no family history of breast cancer. “This shocked everyone, including us,” Esserman said. “It proves family history isn’t a reliable way to decide who needs genetic testing.”

The study also revealed shifting expectations and preferences around breast cancer screening among women. WISDOM took place during the pandemic, which altered people’s willingness to undergo screening. “Women started thinking, ‘I should know my risk to decide if I need to get screened,’ which helped our study,” Esserman noted. “Before COVID, people were hesitant to consider less frequent screening.”

The WISDOM findings align with other breast cancer research questioning the need for aggressive treatment of early, low-grade cancers like DCIS. Earlier this year, a study led by Dr. Shelley Hwang at Duke University found that for some DCIS patients, close monitoring with more frequent mammograms didn’t increase their risk of developing breast cancer compared to those who opted for surgery and radiation to remove the lesions.

These initial findings are just the beginning for WISDOM, which has already enrolled participants for its next phase—focused on whether personalized risk-based screening can prevent breast cancer. “I hope the U.S. adopts a comprehensive risk-based screening program,” Esserman said, pointing out that several European countries (including the U.K., France, and the Netherlands) already use variations of this approach. “These results are incredibly exciting. More screening isn’t better—smarter screening is.”