Denmark screening study finds stage IV breast cancer survival reaches 74.7%

What is the background?

Denmark built one of the world’s longest-running breast screening registries. Copenhagen started population-based mammography screening in 1991, and Funen county followed in 1993. The programme went nationwide between late 2007 and 2010, inviting women aged 50 to 69 for a free mammogram every two years. Two radiologists read each scan independently before a diagnosis is confirmed.

What happened?

Researchers linked Danish national screening records from 2010 to 2019 with death records through 2022. They tracked 817,128 women invited to screening and identified 32,827 breast cancer diagnoses among them. For women whose cancer had already spread to distant organs at diagnosis (stage IV), five-year survival reached 74.7% when the cancer was found through screening, compared with 32.4% for women whose stage IV cancer was found after symptoms appeared outside the screening programme. That screen-detected stage IV survival figure was close to the 72.6% seen in never-screened women diagnosed at the less advanced stage IIIc.

How did it happen?

The team, led by Amy Tickle at King’s College London’s Comprehensive Cancer Centre with co-authors Judith Offman, Bernard North and Peter Sasieni at Queen Mary University of London, and Susanne Fogh Jørgensen and Sisse Njor at the University of Southern Denmark, used Denmark’s national screening and mortality registers to build a register-based cohort study covering January 2010 to November 2022.

Rather than only comparing survival by cancer stage, the researchers compared survival by how the cancer was found: through routine screening, through symptoms in a woman who had previously attended screening, or through symptoms in a woman who had never been screened. Screen-detected stage IV patients received surgery 67% of the time, compared with 23% of never-screened stage IV patients. Median survival with surgery ranged from 4.4 to 6.0 years, against 1.6 to 2.2 years for non-surgical treatment and under two months for patients who received no treatment.

Why does it matter?

The findings, published in JNCI on 19 February 2026, show that even a late-stage cancer diagnosis is not automatically the worst-case outcome, if screening catches it. “Our results show that how breast cancer is detected could impact the patient’s survival chances,” said Amy Tickle. “There is understandably a lot of fear around cancer being found late, but our findings provide reassurance that long-term survival is still possible when it is found during screening.” The authors concluded that estimating breast cancer mortality from stage alone, without accounting for how the cancer was diagnosed, underestimates the real impact of organised screening programmes.

What were the key results?

• 817,128 women invited to Danish national screening were tracked from 2010 to 2022
• 32,827 breast cancer diagnoses identified across the cohort
• Screen-detected stage IV cancer: 74.7% five-year survival, versus 32.4% for never-screened stage IV cases
• Screen-detected stage IV survival (74.7%) closely matched never-screened stage IIIc survival (72.6%)
• 67% of screen-detected stage IV patients had surgery, versus 23% of never-screened stage IV patients
• Study published in JNCI, Volume 118, Issue 6, pages 1073-1080, 19 February 2026

What happens next?

The authors say models that ignore how a cancer was found will underestimate how much breast screening cuts deaths. Denmark has offered breast screening every two years to women aged 50 to 69. Five administrative regions run the service separately. The authors are based at King’s College London, Queen Mary University of London and the University of Southern Denmark. They say screen-detected stage IV cancers deserve further study.

In England, the NHS explains who is invited for breast screening and what a mammogram involves.