Using AI to read mammograms cut risk of developing aggressive breast cancer, study finds

Some aggressive breast cancers can be difficult to detect and don't always show up on mammograms, but a new study out of Sweden has found that artificial intelligence could help.

Mammograms are used to find breast cancers earlier, when they are easier to manage and treat. When radiologists used artificial intelligence to assist their readings, the rate of detection of breast cancers increased, resulting in fewer aggressive and advanced cases, a large trial in Sweden has found.

For the study — published in Thursday's issue of the medical journal The Lancet — more than 100,000 women had mammography screenings. Half were supported by AI and the rest had their mammograms reviewed by two different radiologists, a standard practice in much of Europe known as double reading. It is not typically used in Canada, where usually one radiologist checks mammograms.

The study looked at the rates of interval cancer, the term doctors use for invasive tumours that appear between routine mammograms. They can be harder to detect and studies have shown that they are more likely to be aggressive with a poorer prognosis.

The rate of interval cancers decreased by 12 per cent in the groups where the AI screening was implemented, the study showed.

Lead author, Dr. Kristina Lång, said the large decrease was "a big sigh of relief."

"The great outcomes we have seen [are] very promising," said Lång, a breast radiologist and associate professor of diagnostic radiology at Lynn University in Malmo, Sweden.

In 2024, an estimated 30,500 Canadians were diagnosed with breast cancer, according to the Public Health Agency Canada, which also noted that the probability of surviving at least five years after diagnosis was about 89 per cent.

In 2024, the Canadian Task Force for Preventive Health Care said that mammograms shouldn't be routinely offered to women under 50 who are of average risk, but noted that anyone 40 or over who wants a mammogram should be able to get one every two to three years. This practice hasn't been widely adopted, though some Canadian provinces are moving toward that standard.

In Sweden, population-based breast cancer screening is offered to those between the ages of 40 to 74.

The frequency of screening also differs — in most Canadian jurisdictions, screening typically takes place every 24 months. In Sweden, it's between 18 to 24 months.

Throughout the two-year study, the mammograms that were supported by AI were triaged into two different groups. Those that were determined to be low risk needed only one radiologist to examine them, while those that were considered high risk required two.

The researchers reported that numerically, the AI-supported screening resulted in 11 fewer interval cancers than standard screening (82 versus 93, or 12 per cent).

"This is really a way to improve an overall screening test," Lång said.