It is not normal to have nodules in the breast during chemotherapy for breast cancer, and it is considered that there may be breast hyperplasia and fibroma in the breast. 1. Breast hyperplasia: it is usually caused by excessive secretion of estrogen and endocrine disorders. Breast hyperplasia may occur, and localized nodules may also appear, mostly accompanied by breast swelling and pain and other symptoms. 2. Fibroid: If patients take breast-conserving surgery, only part of the breast tissue is removed. After surgery, endocrine disorders may occur in the process of treatment, when the body’s hormone level is disturbed, it may lead to fibroid lesions. The main manifestation is nodules inside the breast, the size of the nodules is usually between 1-3 centimeters, the texture is tough, and there is usually no pressure pain. Nodules in the breast during breast cancer chemotherapy may also be tumor metastasis, recurrence, it is recommended to go to the hospital in time, standardized examination and treatment.