The duration of side effects of radiotherapy for breast cancer varies slightly depending on the side effects. For example, acute radiation dermatitis can be fully recovered within 1 month after the end of radiotherapy; radiation pharyngitis can be recovered within 1 month after the end of radiotherapy; some patients can even recover within 1-2 weeks after the cessation of radiotherapy. Radiation pneumonia usually starts to appear within 1-6 months after the end of radiotherapy, and the duration, varies. However, the percentage of radiation pneumonia, especially symptomatic radiation pneumonia, in breast cancer radiotherapy is generally not very high, probably less than 5%.