In breast cancer, CA15-3 is significantly increased in 30% - 50% of patients, but in early breast cancer, its positive rate is only about 20% - 30%. It is often used to observe the recurrence of breast cancer after treatment and monitor the metastasis of breast cancer. In metastatic ovarian cancer, colon cancer, more than 100000 u/l, bronchial cancer and pregnancy, its serum levels also increased to varying degrees.