Most of the normal values are 0-25U/ml or 0-35U/ml, and the values vary somewhat from hospital to hospital or medical unit to medical unit. CA15-3 has a certain sensitivity and specificity mainly in breast cancer and can be used to monitor the efficacy of breast cancer treatment as well as to detect recurrence and metastasis early. However, it does not mean that an elevated CA15-3 necessarily means that you have breast cancer, nor does a normal CA15-3 completely exclude breast cancer. For breast cancer, the gold standard for diagnosis is pathological diagnosis. If there is no pathological diagnosis, the tumor can be initially searched and judged by ultrasound, X-ray, CT and other imaging examinations. Ultrasound and CT examinations are commonly used clinical examinations. Through imaging examination, tumor size and location can be found, and the nature of the mass can be initially judged according to the imaging features combined with clinical manifestations. Finally, the diagnosis is clarified by pathological examination.