AI breast cancer screening cuts interval cancers by 12% in first randomized controlled trial

Reviewed byNidhi Govil

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A groundbreaking Swedish trial involving over 100,000 women found that AI breast cancer screening reduced interval cancers by 12% and detected 9% more cancers overall. The randomized controlled trial shows AI-assisted mammograms can spot aggressive breast cancer earlier while cutting radiologist workload by 44%, though experts urge cautious implementation.

AI Breast Cancer Screening Delivers Major Reduction in Aggressive Tumors

Artificial intelligence has demonstrated its ability to transform breast cancer detection in the first randomized controlled trial of its kind. The MASAI trial, published in The Lancet, found that AI breast cancer screening reduced interval cancers by 12% among more than 100,000 Swedish women screened between April 2021 and December 2022

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. These interval cancers—aggressive tumors that develop rapidly between scheduled screenings—are particularly dangerous and harder to treat effectively.

Source: France 24

Source: France 24

Led by Kristina LÃ¥ng at Lund University, the study randomly assigned participants to either AI-assisted mammograms or standard double reading by radiologists

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. The results showed 1.55 interval cancers per 1,000 women in the AI-supported group compared to 1.76 per 1,000 in the control group

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. "When we got the results, we were extremely thrilled," says LÃ¥ng

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Higher Cancer Detection Rate Without Increasing False Positives

The AI system, developed by ScreenPoint Medical and trained on more than 200,000 mammography examinations from over ten countries, achieved a 9% increase in early cancer detection

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. In the AI-supported mammography group, 81% of cancer cases were detected at screening compared to 74% in the control group

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. Critically, false positives remained similar at 1.5% in the intervention group versus 1.4% in the control group

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Source: Sky News

Source: Sky News

The technology works by ranking mammograms on a scale of 1 to 10 based on cancer likelihood. Scans scoring 1 to 9 receive assessment by one experienced radiologist, while those scoring 10 undergo double reading by two radiologists

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. This approach previously showed a 29% increase in cancer detection without raising false positives

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Fewer Interval Cancers and Aggressive Subtypes Detected

The two-year follow-up revealed substantial reductions in the most dangerous cancer types. The AI group experienced 16% fewer invasive cancers, 21% fewer large tumors, and 27% fewer aggressive sub-type cancers compared to standard screening

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. This improvement likely stems from AI's superior ability to detect cancers at very early stages that human radiologist might overlook

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Estimates suggest 20-30% of interval cancers could have been spotted at the preceding mammogram, making this reduction particularly significant

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. With breast cancer causing more than 2 million diagnoses globally each year and remaining the leading cause of death in women aged 35 to 50, earlier detection could save substantial lives

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Reduce Radiologist Workload While Maintaining Human Oversight

Interim safety results published in 2023 showed a 44% reduction in screen-reading workload for radiologists

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. First author Jessie Gommers notes the results "potentially justify using AI to ease the substantial pressure on radiologists' workloads, enabling these experts to focus on other clinical tasks, which might shorten the waiting times for patients".

Source: New Scientist

Source: New Scientist

Crucially, researchers emphasize that AI-assisted mammograms still require at least one human radiologist to perform readings with AI support

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. "Women that participate in screening say they do not want to have AI as a standalone tool, they want to have a human in the loop, and I agree with them," says LÃ¥ng

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Cautious Implementation and Cost-Effectiveness Considerations

Despite promising results, LÃ¥ng expects widespread adoption to take time. The AI approach will likely roll out across south-west Sweden within months, but other European countries may need five years to complete trials justifying implementation

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. "Introducing AI in healthcare must be done cautiously, using tested AI tools and with continuous monitoring in place," LÃ¥ng emphasizes

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Cost-effectiveness remains a key consideration. Some estimates suggest AI assistance warrants investment if it cuts interval cancer rates by at least 5%—a threshold this trial surpasses

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. However, Jean-Philippe Masson from France's National Federation of Radiologists notes these systems are expensive and prone to overdiagnosis concerns

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Dr. Sowmiya Moorthie from Cancer Research UK urges caution: "This study helps to address concerns, but the results are from a single centre, so more research will be needed to know for sure if this will help save lives"

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. Ongoing trials in the UK will help determine effectiveness across different ethnicities and screening frequencies

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