If there is a mild elevation of glycoconjugate antigen 153, it may be seen in breast hyperplasia. Therefore, it is recommended to have a breast ultrasound examination if the elevation is mild. If the glycogen antigen 153 is significantly elevated, breast ultrasound and, if necessary, breast enhancement nuclear magnetic examination are recommended to clarify the diagnosis. If the glycogen antigen 153 is significantly elevated and a clear mass is palpable in the breast, or if a suspicious mass is detected by MRI, biopsy is recommended, and if the biopsy is clearly malignant, systemic examination is recommended, and surgery is recommended if there is an opportunity for surgery.