# County Durham NHS Trust medical investigation > Live situation record from CLSTR: https://clstr.news/situations/county-durham-nhs-trust-medical-investigation > Updated: 2026-09-24T14:31:00.000Z. Sources: 7. Developments: 2. An investigation into the County Durham and Darlington NHS Foundation Trust (CDDFT) has uncovered significant failures in breast cancer care. A preliminary review of 539 cases between January 2023 and February 2025 identified that 315 patients suffered harm, including one death and multiple cases of moderate or severe injury. The findings highlighted 20 instances of unnecessary mastectomies, 32 cases of excessive surgery, and 20 instances of delayed cancer diagnoses. Chief Executive Steve Russell described the situation as ‘utterly unacceptable’, and both the National Crime Agency and Durham Police have launched investigations into potential criminal offences. Following these findings, the trust has announced an extensive expansion of its review. The investigation may now encompass up to 4,500 cases, potentially looking back to 2015 when service reconfigurations first raised concerns. If the review extends to its full scope, the process could continue until 2031. ## Timeline ### 2026-09-24: County Durham NHS Trust to review 4,500 breast cancer cases after unnecessary surgeries A major UK NHS scandal has prompted a five-year review of up to 4,500 breast cancer cases after 20 unnecessary mastectomies and hundreds of patients were found to have suffered harm. 2 sources. https://clstr.news/cluster/county-durham-nhs-trust-to-review-4500-breast-cancer-cases-after-unnecessary-surgeries ### 2026-09-18: County Durham NHS Trust investigation reveals unnecessary mastectomies An NHS trust in County Durham is under investigation after a review found 20 women underwent unnecessary mastectomies and hundreds of others suffered harm during breast cancer treatment. 5 sources. https://clstr.news/cluster/county-durham-nhs-trust-investigation-reveals-unnecessary-mastectomies --- Cite as: County Durham NHS Trust medical investigation. CLSTR, https://clstr.news/situations/county-durham-nhs-trust-medical-investigation