COVID-19 pandemic: a new cause of unplanned interruption of radiotherapy in breast cancer patients.

The purpose of this study was to investigate the impact of the coronavirus disease 2019 (COVID-19) pandemic on patients undergoing radiotherapy by comparing the patterns of unplanned radiotherapy interruption before and after the COVID-19 pandemic. We enrolled patients who received their first dose of radiotherapy for breast cancer between January 28 and July 31, 2019 and between January 28, 2020, and July 31, 2020. We compared the radiotherapy interruption patterns in 2019 with those in 2020 to analyze the impact of the COVID-19 pandemic on treatment interruption. Between January 28 and July 31, 2019, 287 patients with breast cancer received radiotherapy. Among them, 19 patients (6.6%) experienced treatment interruption; the reasons for treatment interruption were radiotherapy-related side effects (10 patients, 52.6%), other medical reasons (three patients, 15.8%), and personal reasons (six patients, 31.6%). Between January 28 and July 31, 2020, 279 patients with breast cancer received radiotherapy. Among them, 23 patients (8.2%) experienced treatment interruption; the reasons for treatment interruption were radiotherapy-related side effects (eight patients, 35%) and COVID-19 screening clinic-related reasons (six patients, 26.1%). Among the six patients with screening clinic-related causes of radiotherapy interruption, five had asymptomatic fever and one had mild cold-like symptoms. The duration of treatment interruption was longer in patients with screening clinic-related interruptions than in those with interruptions because of other causes (p = 0.019). Multivariate analysis showed that cancer stage and radiotherapy volume did not significantly affect treatment interruption. The radiotherapy of certain patients was suspended despite the lack of a confirmed COVID-19 diagnosis. Precise and systematic criteria for the management of patients with suspected COVID-19 are needed, and the opinion of radiation oncologist in charge of the patient must also be considered.