Thousands of calls have been made to a helpline after it emerged up to 270 women may have died early due to a breast cancer screening failure.
Health Secretary Jeremy Hunt revealed on Wednesday that 450,000 women aged 68 to 71 had not been invited to their final routine check.
An independent review has been launched into the computer error, which was discovered in January but dates back to 2009.
Mr Hunt said between 135 and 270 women could have had their lives shortened as a result of the mistake.
A dedicated helpline for those who may be affected had received around 8,000 calls by Thursday evening, according to Public Health England, which oversees the screening programme.
:: 'No scandal': Breast cancer researchers defend trial
The Breast Cancer Care charity said it had also seen a surge in calls to its own helpline, adding that many women felt angry and confused.
Baroness Delyth Morgan, chief executive at Breast Cancer Now, described the mistake as a "colossal systemic failure".
Women in England between the ages of 50 and 70 are automatically invited for breast cancer screening every three years.
Of those who missed invitations, 309,000 are estimated to still be alive.
All of those affected who are living in the UK and registered with a GP will be contacted before the end of May.
The women will be given the opportunity to have a new appointment.
Mr Hunt has conceded that "administrative incompetence" meant some families may have lost, or may be about to lose, a loved one to cancer.
Women and the families of those who may have been affected by the failures have demanded answers over the failures.
Widower Brian Gough said his wife Trixie did not receive a letter inviting her to go for a screening in 2009.
A scan in October 2010 revealed she had stage-three breast cancer.
The 77-year-old, from Norfolk, has said he was "shell-shocked" by the news.
He added: "There has always got to be some blame, these things don't just happen, it is never the computer that goes wrong, it is the person that put the information in or took it out.
"Somebody somewhere along the line has made a massive error – we are talking 450,000 letters that should have gone out."
Mr Gough's wife missed the wedding of her grandson as she was too ill to attend, and died just before her granddaughter's nuptials.
He continued: "All of that she missed because she didn't get diagnosed and she didn't know anything about it until a year too late."
Former NHS nurse Patricia Minchin said she was not offered her final screening in 2013 and was diagnosed with breast cancer two years later.
The 75-year-old from Bushey, Hertfordshire, told Sky News: "When my second letter should have arrived in 2013, when I was 70, I thought I must have misunderstood the age cut-off and that was that.
"I believed I was out of the 'most at risk' age for breast cancer.
"I went about my life for two years – but I'd been lulled into a false sense of security.
"I now know I should have been sent a letter.
More from Breast screening scandal
"That letter would have led to a scan that could well have caught my cancer early and saved me from the harsh levels of cancer treatment that I had to endure."
The official helpline for those who think they may be affected is 0800 169 2692.
[contf]
[contfnew]
Sky News
[contfnewc]
[contfnewc]
