Effects of antipsychotic drugs during radiotherapy in breast cancer in South Korea: a retrospective cohort study

In this study, we aimed to investigate the nationwide utilization of antipsychotic drugs (APDs) during radiotherapy and evaluate their association with survival in patients with breast cancer. This retrospective cohort study used the National Health Insurance Service database in Korea and included patients diagnosed with breast cancer from 2010 to 2020 who received radiotherapy. The APDs included in the analysis were aripiprazole, quetiapine, olanzapine, risperidone, haloperidol, and chlorpromazine, and the APD prescription details included prescription time, dosage, and duration. Among 170,226 patients with breast cancer treated with radiotherapy, 3361 (1.97%) received APD during radiotherapy. Use of APDs was significantly associated with higher mortality in all patients and in a subgroup of patients excluding those with metastasis or other cancers. Among patients taking APD during radiotherapy, those with accompanied psychiatric history and long-term APD use for ≥ 3 months were associated with lower mortality, whereas patients who started APD during radiotherapy had higher mortality than those who started APD before radiotherapy. The high mortality observed in breast cancer patients using APDs during radiotherapy could be influenced by the underlying conditions that necessitated APD use. Further studies are needed to determine the effects of APDs during radiotherapy in patients with breast cancer.