AI-Supported Mammography Outperforms Standard Breast Cancer Screening, Major Lancet Study Finds

The use of artificial intelligence in breast cancer screening has been shown to significantly improve detection outcomes compared to standard mammography, according to full results from a large Swedish trial published in The Lancet.

The study, based on Sweden’s national breast cancer screening programme, found that AI-supported mammography not only detected more cancers at the time of screening but also reduced cancer diagnoses in the years following screening by 12 per cent—a key indicator of screening effectiveness.

Researchers also reported a 44 per cent reduction in screen-reading workload for radiologists, highlighting AI’s potential to ease pressure on overstretched healthcare systems.

Largest Randomised Trial of AI in Cancer Screening

“This is the first randomised controlled trial investigating AI in breast cancer screening and the largest study to date examining AI use in cancer screening overall,” said lead author Dr Kristina Lang, a breast radiologist and clinical researcher at Lund University, Sweden.

She noted that AI-supported screening improves early detection of clinically relevant cancers, leading to fewer aggressive or advanced cases being diagnosed between routine screenings.

Between April 2021 and December 2022, more than 105,900 women were randomly assigned to either AI-supported mammography or standard double reading by radiologists without AI support.

Fewer Interval Cancers, Earlier Detection

During a two-year follow-up period, the AI-supported group recorded 1.55 interval cancers per 1,000 women (82 cases among 53,043 participants), compared with 1.76 interval cancers per 1,000 women (93 cases among 52,872 participants) in the standard screening group representing a 12 per cent reduction.

Interval cancers are malignancies detected between scheduled screening appointments after a previous negative result and are often more aggressive.

The study also showed that 81 per cent of cancer cases in the AI-supported group were detected during screening, compared with 74 per cent in the standard screening group a nine per cent increase in screen-detected cancers.

No Increase in False Positives

Importantly, the use of AI did not lead to a higher rate of false positives. False-positive rates were nearly identical, at 1.5 per cent for AI-assisted screening and 1.4 per cent for standard mammography.

The AI system used in the trial was trained, validated, and tested on more than 200,000 mammography examinations from multiple institutions across over ten countries.

Potential for Widespread Adoption

Researchers from Sweden, Norway, Denmark, and the Netherlands found that women who underwent AI-supported screening were less likely to be diagnosed with advanced or aggressive breast cancer in the two years following screening.

“Widespread adoption of AI-supported mammography could help detect more cancers at an early stage while also reducing workload pressures on radiologists,” Dr Lang said.

The findings build on interim results from the Mammography Screening with Artificial Intelligence (MASAI) trial published in August 2023, which showed a 20 per cent increase in cancer detection using AI compared to standard screening.

Experts say the results strengthen the case for integrating AI into national breast cancer screening programmes worldwide, particularly as healthcare systems face rising demand and workforce shortages.