CHIBA -- The Chiba Cancer Center here mistakenly removed the entire right breast of a female patient with early-stage breast cancer despite the fact that there was no need for an immediate mastectomy, hospital officials disclosed on Dec. 25.
The mistake occurred when the cellular examination results of the patient, a Chiba Prefecture resident in her 30s, were confused with another patient in her 50s with progressive breast cancer.
The center in Chiba's Chuo Ward has set up an internal accident investigation board including outside experts, and it will have its first meeting next month.
According to center officials, a breast tissue sample from the woman in her 30s with suspected breast cancer was extracted with a needle from the affected area in mid-October for tests. After her tissue specimen was mistakenly switched with that of the other patient who had an appointment at the center on the same day, she was told in early November that the entire breast would need to be removed. The younger woman in fact had early-stage cancer, however, for which follow-up examinations would have been sufficient.
The operation was performed in early December, after which the woman was discharged in stable condition.
On Dec. 15, the pathologist examining the breast tissue removed during the surgery realized that it was different from the specimen taken during the patient's examination in October. The identity mix-up was discovered two days later, after genetic tests were performed on the tissue samples from both patients.
Meanwhile, a follow-up examination was also performed on the patient in her 50s with progressive breast cancer after it was determined that the test results of her specimen did not match those from the end of October.
Under normal hospital procedure, diagnosis and treatment department staff place tissue samples inside formalin containers labeled with the patient's name, and the containers are then sent on to the pathology department for examination. A number of doctors, nurses and clinical laboratory technicians are involved in the processes.
The specimens of the two patients were apparently switched at some point during this progression. According to a center representative, "We have not yet identified which process was associated with the error at this point. We plan to wait for the results of the internal accident investigation board."
The center held meetings with the patients and their families between Dec. 18 and 22 to explain what had happened and offer apologies. The center is also reviewing the possibility of offering compensation.
During a Dec. 25 press conference at the Chiba Prefectural Government office, Chiba Cancer Center Director Matsuo Nagata commented, "We deeply apologize to the patients, their families, and the citizens of this prefecture. We will conduct a thorough investigation to determine and verify the cause of this incident, and will immediately implement measures to ensure that nothing similar occurs again."