A breast cancer screening error affecting 450,000 women may have led to hundreds of lives being cut short, Health Secretary Jeremy Hunt has revealed.
Mr Hunt told the Commons that a "computer algorithm failure" dating back to 2009 had meant many women aged 68 to 71 were not invited to their final routine screening.
It is not known whether any delay in diagnosis resulted in avoidable death, but it is estimated that between 135 and 270 women had their lives shortened as a result, he said.
An independent review has been launched into the "serious failure" in the programme, overseen by Public Health England (PHE), which was discovered in January.
Mr Hunt told the Commons: "Earlier this year PHE analysis of trial data from the service found that there was a computer algorithm failure dating back to 2009.
"The latest estimates I have received from PHE is that as a result of this between 2009 and the start of 2018 an estimated 450,000 women aged between 68 and 71 were not invited to their final breast screening.
"At this stage it is not clear whether any delay in diagnosis resulted in any avoidable harm or death and that is one of the reasons I am ordering an independent review to establish the clinical impact.
"Our current best estimate - which comes with caveats as it's based on statistical modelling rather than patient reviews and because there is currently no clinical consensus about the benefits of screening for this age group - is that there may be between 135 and 270 women who had their lives shortened as a result.
"I am advised that it is unlikely to be more than this range and may be considerably less.
"However, tragically, there are likely to be some people in this group who would have been alive today if the failure had not happened."
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 their 68th and 71st birthday.