A breast-screening error that may have shortened the lives of 270 women could have affected thousands more, according to a leading expert.

Earlier this month Jeremy Hunt told the Commons an estimated 450,000 women around the age of 70 were not invited to final screenings between 2009 and 2018.

He said: “Tragically there are likely to be some people in this group who would have been alive today if the failure had not happened.”

Professor Peter Sasieni, Deputy Director of the Centre for Cancer Prevention at Queen Mary University of London, has claimed the error could actually date back to 2005.

In a letter published in The Lancet, he said: “Data that could have alerted people to the lack of invitations being sent to women aged 70 was publicly available, but no one looked at it carefully enough.”

He added that although it should not be viewed as “a major public health failure”, it would be only right “to investigate how this error occurred and why it was not spotted for so long”.

“It is important that the computer systems used to run our cancer screening programmes are reviewed and, if necessary replaced – and that detailed anonymous data are made available for independent scrutiny,” he said.

Of the estimated 450,000 women who are known to have missed invitations since 2009, 309,000 are estimated to still be alive. 

All those living within the UK who are registered with a GP will be contacted about the error before the end of May, with the first 65,000 letters going out this week, Hunt said. 

Women who have already received a terminal cancer diagnosis are likely to be among those to receive a letter informing them their screening appointment was missed, the House of Commons heard. 

Hunt said he realised it would be devastating news for those whose health had already suffered. 

“I apologise wholeheartedly and unreservedly for the suffering caused,“ Hunt added, promising that all those affected who wished to be screened will receive an appointment in the next six months. 

Affected families will also be offered support and compensation, he said.