Pneumonia after radiation therapy for breast cancer is generally called radiation pneumonia, which usually occurs 1-6 months after the end of radiation therapy, and very rarely occurs during radiation therapy. The symptoms of radiation pneumonia in breast cancer are usually mild and may include dry cough, throat discomfort, fever and chest tightness. When these symptoms occur, only symptomatic treatment is needed, such as cough medication; more serious radiation pneumonia may need to be treated, such as severe cough, high fever, and very obvious difficulty in breathing, which may need to be treated with drugs, mainly high-dose hormones, anti-inflammatory drugs and oxygen therapy. The percentage of symptomatic radiation pneumonia is generally low, probably below 5%.