Women who don’t attend their first mammogram face a 40% higher risk of dying from breast cancer in the long-term, a Swedish study has reported.

The increased risk is largely down to delayed detection and targeting this group could help reduce deaths at a population level, the researchers concluded in the BMJ.

Analysis of Swedish registry data for 433,000 women who received their first screening invitation between 1991 and 2020 showed almost a third (32.1%) did not attend their initial screening.

They were persistently less likely to attend subsequent screenings and were more likely to be diagnosed with advanced stage breast cancer than participants, the researchers found.

Study first author, Ziyan Ma, a doctoral student at the Department of Medical Epidemiology and Biostatistics, Karolinska Institute, said: ‘Skipping the first mammogram is a strong indicator of who is at risk of late detection and higher mortality. Our results show that missing the first mammogram is not just a one-time choice, but often marks the beginning of a long-term pattern of not attending check-ups.’

Delayed breast cancer detection

The risk of developing stage 3 cancer was approximately 1.5 times higher, and for stage 4, the risk was as much as 3.6 times higher for those who missed their first mammogram compared to those who participated in it.

Over 25-years of follow up and taking into account social, economic, reproductive and health-related factors, 9.9 per 1,000 women who did not attend their first screening died of breast cancer compared with seven per 1,000 who did. This difference corresponds to a 40% higher risk of dying from breast cancer.

But the breast cancer rate was similar between the two groups, the researchers reported at 7.8% of those who did attend their first screening and 7.6% of those who did not.

It suggests that the higher deaths among non-participants likely reflects delayed detection rather than increased incidence, the researchers concluded.

The study's last author, Kamila Czene, professor at the Department of Medical Epidemiology and Biostatistics, Karolinska Institute, added: ‘Family history is a well-known, unchangeable risk factor for breast cancer. Our study shows that missing the very first screening examination carries a similar mortality risk – but unlike family history, this is a behaviour that we can change.

‘Since over 30% of women skip their first screening, increased participation could save many lives. Since this group can be identified early, decades before deaths occur, healthcare providers have a chance to intervene with reminders or support to encourage participation.’

A linked editorial noted that ‘ensuring that women are informed, supported, and empowered to participate in their first screening should be a shared goal across the healthcare system’.

Previous European research found that adopting a risk-stratified approach to breast cancer screening could help improve the benefit-to-harm ratio and the cost-effectiveness of screening programmes.

Mammography in the UK

The latest figures for England suggest around 70% of women take up the invitation for a mammogram – similar to rates noted in Sweden.

Earlier this year it was revealed that more than 5,200 people were not invited for routine screenings including for bowel, breast and cervical cancers, due to issues with ‘incomplete’ GP registrations.

In May, UK researchers said additional scans on top of mammography can detect more cases of breast cancer when offered to women with very dense breast tissue.

A trial of more than 9,000 women at 10 sites found that extra imaging done with abbreviated MRI or contrast-enhanced mammography picked up cancers that had not been detected with standard mammogram.

If the approach was adopted on the NHS, the extra scans could treble cancer detection, potentially saving up to 700 lives a year in the UK, the researchers at the University of Cambridge reported in The Lancet.

Claire Rowney, chief executive at Breast Cancer Now, said: ‘Despite breast screening being the most effective way to find breast cancer early, when survival is highest, thousands of women in the UK continue to miss out on this vital health check and those who miss their first appointment are much less likely to go in future.

‘With a worryingly high number of women in the UK not attending their first breast screening appointment, we urgently need to ensure women are encouraged to get screened, and that screening is easily accessible to all invited.’

Previous research for lung cancer has shown that providing patients with a specific appointment time for lung cancer screening results in higher attendance than sending them an open invitation.