Objective:To observe the serum VEGF/ES ratios before and after operation and at clinical relapse in patients with breast cancer, and to discuss the potential effect of tumor surgery and postoperative relapse on the angiogenesis balance. Methods:The serum VEGF and ES levels of 59 cases of breast cancer before and after operation and at clinical relapse were determined using competitive enzyme immunoassays and ELISA, respectively, and compared with the results of 30 cases of benign breast tumors and 59 cases of normal controls. Results:(1) Preoperatively, the serum ES and VEGF levels of breast cancer patients were significantly elevated, as compared to the other 2 groups, and the VEGF/ES ratio was 9.1. Postoperatively, at 3 weeks, VEGF level decreased significantly and ES remained at a high level. The VEGF/ES ratio was 3.3. (2)At the time of clinical relapse, serum VEGF level was followed by marked elevation, and the VEGF/ES ratio increased up to 14.2. Multivariate analyses showed that the postoperative VEGF/ES ratio was an independent factor related to the postoperative recurrence of breast cancer. Conclusions:Breast cancer surgery may affect the balance between serum VEGF and ES, and the determination of VEGF/ES ratio can have auxiliary value in the assessment of prognosis of breast cancer patients.