Patients undergoing postoperative radiation therapy for breast cancer will experience skin hyperpigmentation at 3-4 weeks of radiation therapy, and patients may feel that their skin has darkened. As radiotherapy progresses, erythema may appear on the skin, and even small localized ulcers may appear towards the end of radiotherapy. These erythemas and localized breakouts usually heal completely within 1 month after the end of radiation therapy. After healing, the patient’s skin will appear red, and the patient will still feel a difference in his or her skin compared to the skin on the opposite side. This difference persists until 3-6 months after the end of radiation therapy, and usually there is no significant difference between the patient’s skin and that of the opposite side 6 months after the end of radiation therapy.