Up to 450,000 women may have missed out on their final routine breast screening because of an IT error.
Health Secretary Jeremy Hunt revealed today that as a result hundreds of women "had their lives shortened."
The "computer algorithm failure" that occurred in 2009 and ran through to 2018 meant that many women who were aged between 68 and 71 during that period were not sent their final breast screening invitation.
Women in England between the ages of 50 and 70 are currently automatically invited for breast cancer screening every three years because the risk of breast cancer increases with age.
It is not known whether any delay in diagnosis resulted in avoidable death but Hunt said the "serious" error meant between 135 and 270 women "had their lives shortened," according to early estimates.
"Tragically, there are likely to be some people in this group who would have been alive today if the failure had not happened," he said.
Of those who missed invitations, 309,000 are estimated to still be alive and all those living in the UK who are registered with a GP will be contacted before the end of May. The first 65,000 letters will be going out this week.
Those under the age of 72 will receive an appointment letter informing them of the time and date, while those over 72 will also be offered a screening and have access to a helpline to decide if it will be beneficial.
Mr Hunt apologised "wholeheartedly and unreservedly for the suffering caused" and promised an independent review of the NHS breast screening programme.
The review, expected to report in six months, will be chaired by Lynda Thomas, the chief executive of Macmillan Cancer Support, and leading oncologist Professor Martin Gore.
"As well as apologising to the families affected, we would wish to offer any further advice they might find helpful including the process by which we can establish whether the missed scan is a likely cause of death and compensation is therefore payable," Mr Hunt said.
The Health Secretary said Scotland uses a different IT system and while the systems in Wales and Northern Ireland are similar "neither believe they are affected".
Breast cancer is the most common cancer in the UK, with around 150 diagnoses every day - accounting for 15% of all new cancer cases.
Breast screening uptake in the UK has fallen slightly since 2010/11. This is despite screening being the most effective at diagnosing breast cancer at an early stage.
Breast cancer survival is improving and has doubled in the last 40 years in the UK. Around two-thirds (65%) of women diagnosed with breast cancer in England and Wales survive their disease for twenty years or more.
Emma Greenwood, Cancer Research UK's director of policy and public affairs, said: "It's very concerning to learn that so many women have not received an invitation to screening over a prolonged period of time.
"If you suspect you have been directly affected by this or if you are over 50 and haven't had a mammogram in the last three years and would like one, the NHS Choices website provides further information and the option to contact your local unit to book an appointment."
"It's worth remembering that many breast cancers are still found by women themselves, outside of the screening programme, so if you notice any unusual changes in your breast, see your GP straight away."
If you've been affected by the NHS error, please get in touch at email@example.com and @itvnews.