An investigation has revealed that twenty women underwent unnecessary mastectomies while being treated for breast cancer at the County Durham and Darlington Foundation Trust. In total, 32 women received excessive surgery, where a wide local excision would have been appropriate. Of this number, 20 women had a mastectomy without clinical need. Furthermore, delayed diagnosis of breast cancer was identified in another 20 women. These findings emerged from a review of more than 500 cases in response to serious failures of care at the trust. An internal review of other affected patients is ongoing, including those who came forward through a helpline established last year. There have been longstanding and escalating concerns about the quality of breast cancer care, governance, and patient experience at this trust.