Cancer charities have demanded answers after a computer glitch led to 450,000 cancelled breast screenings and shortened up to 270 lives, Sky News reported.
Health Secretary Jeremy Hunt apologized for the scandal in the Commons on Wednesday, revealing that some women in the group "would have been alive today" if the failure had not happened.
A Whitehall source told the Daily Mirror that an IT "upgrade" to the system in 2016 revealed a "computer algorithm failure" subsequently found to date back to 2009.
The glitch was flagged up by NHS chiefs from at least three trusts last year but was only made public by Mr Hunt on Wednesday.
Breast Cancer Now chief executive Baroness Delyth Morgan branded it "a colossal systematic failure".
She said: "That hundreds of thousands of women have not received screening invitations they've been relying upon, at a time when they may be at most risk of breast cancer, is totally unacceptable.
"For those women who will have gone on to develop breast cancers that could have been picked up earlier, this is a devastating error."
Macmillan Cancer Support chief executive Lynda Thomas said: "It's deeply shocking so many women have been missed from breast cancer screening over a number of years.
"It's absolutely critical we understand what happened and make sure this never happens to another person again."
Breast Cancer care chief executive Samia al Qadhi called the NHS error "appalling".
She said: "Hundreds of thousands of women have been failed by this appalling error and some have had their lives shortened as a result.
"It is shocking that almost a decade has passed before this mistake was discovered. This incompetence must not be allowed to happen again".
The records of the women participating had a "flag" on the NHS system when the trial began in 2009, resulting in them not receiving any more routine invitations for screening.
Women in England between the ages of 50 and 70 are currently automatically invited for breast cancer screening every three years.
They should receive their final invitation between the age of 68 and 71. The failure affected this group.
As a result, around 450,000 women in England missed out on the appointment; of these, 150,000 have died since.
The estimated 309,000 women who are still alive and living in the UK will be contacted, with 65,000 letters being sent out this week.
In his statement to the Commons, Mr Hunt apologised "wholeheartedly and unreservedly for the suffering caused".