Sudden swelling of breasts after several years of menopause may be caused by trauma, breast hyperplasia, mastitis or breast cancer. 1. Trauma: Breast swelling after several years of menopause may be caused by trauma, if the breasts are hit or touched by external forces, it will cause breast swelling and pain. 2. Breast hyperplasia: Sudden swelling of the breasts after several years of menopause may be related to breast hyperplasia, which is usually caused by adverse mental factors such as mental tension and emotional excitement, and can be manifested as breast swelling, lumps, nodules, and accompanied by tenderness. 3. Mastitis: Hormonal disorders after a few years of menopause can lead to blockage of the milk ducts, resulting in mastitis, which can cause pain and swelling of the breasts. 4. Breast cancer: Postmenopausal middle-aged and old-aged women are the high incidence of breast cancer. Early symptoms of breast cancer are breast lumps, breast skin abnormalities, nipple and areola inversion, and breast swelling. If a patient’s breast suddenly swells after a few years of menopause, she should go to the hospital immediately to do relevant examinations and clarify the cause of the disease under the guidance of the doctor, so as to avoid delaying the disease and causing adverse consequences.