The board decision came after it was revealed 20 women needlessly had their breasts removed.

Chief executive Steve Russell said: ‘Today's decision means we will look further back, one year at a time. We will carefully consider what we find at each stage and use that to decide what happens next. We will continue to listen to women and families and be open about what we find.

‘We know the look-back itself can bring further worry and distress. Our support will remain open and available throughout. Where we identify concerns about someone's care, we will contact them directly and make sure they receive the information and support they need.

‘We cannot change what happened, but we can continue to listen, support those affected and do everything we can to get this next stage right.'

A review of 1,472 breast surgery cases from January 2023 to February 2025 is ongoing, but today's decision means a further 4,500 cases will be considered.

Chloe Gibson, medical negligence solicitor at Slater and Gordon, said 2015 had been selected as an arbitrary date, highlighting red flags as far back as 2012.

She said the trust was ‘failing to grapple with the scale of the issue' and called for regional or national level intervention.

The solicitor also repeated a call for a public inquiry.

A Department of Health and Social Care spokesperson said: ‘What has happened in Durham is deeply distressing and we are profoundly sorry to all the women who have been affected. No one should undergo a mastectomy, or any other major treatment, unless it is genuinely required, and every patient must be able to trust that the care they receive is safe, effective, and consistent with their diagnosis.

‘Patients and families deserve answers about how these failings happened and confidence that every necessary lesson will be learned. The trust is working to establish the full facts and identify everyone who may have been affected, and it is right that it is expanding the scope of its review. We will continue to monitor that work closely, ensure it is completed as quickly as possible, and assess what further action is needed once its findings are known.'