More than 5,000 people who should have been offered cancer or other types of routine screening did not receive invitations because of an error dating as far back as 2008, NHS England says.
Those affected have now been notified and given details of a dedicated helpline for support.
About 10 people are thought to have since died, but it is not clear whether any screening could have prevented those deaths.
The screening included checks for possible cervical, breast and bowel cancer, as well as abdominal aortic aneurysm.
The error first came to light in 2024, when some people contacted the health service to say they had not received invitations.
The issue was caused by cases where patients’ GP registration process hadn’t been fully completed by practices, meaning their details did not flow through to NHS screening IT systems to invite eligible people for routine screening.
NHS England believes a total of 5,261 people have been affected.
Steve Russell, NHS national director for vaccinations and screening, said: “This issue has now been fixed and everyone affected will be offered support and any catch-up screening as soon as possible, including where they may now be above screening age.
“We would like to extend our sincere apologies to those affected for this error and any additional worry this may have caused. Anyone who is concerned they may have missed an invitation to screening can call our dedicated helpline for support and further information.”
Around 15 million people are invited to NHS screening every year.
NHS England says it has issued guidance to GP Practices and Integrated Care Boards to make sure all patient registrations are fully completed and has put in place new measures to ensure all eligible people are invited for screening.
Anyone in this group that is no longer eligible for screening will be able to have their screening if they choose to opt in. Details of how to do this are set out in the letters that have been sent to those affected.
