Lactation following conservation surgery and radiotherapy for breast cancer. A 38-year-old woman with early stage invasive breast cancer was treated with wide excision of the tumor, axillary lymph node dissection, and breast irradiation. Three years later, she gave birth to a normal baby. She attempted breast feeding and had full lactation from the untreated breast. The irradiated breast underwent only minor changes during pregnancy and postpartum but produced small amounts of colostrum and milk for 2 weeks postpartum. There are only a few reports of lactation after breast irradiation. These cases are reviewed, and possible factors affecting breast function after radiotherapy are discussed. Because of scant information available regarding its safety for the infant, nursing from the irradiated breast is not recommended. 