Evaluation of serum big endothelin-1 for the diagnosis and prediction of disease recurrence in breast cancer patients

Big endothelin-1 (big ET-1) is the biological precursor of endothelin-1 (ET-1) and it is known as an indicator for the degree of activation of endothelin system. Therefore, this study was designed to investigate the serum big ET-1 levels in newly diagnosed primary breast cancer patients; before surgery and after adjuvant therapy. In addition this study was also aimed at examining the correlation between big ET-1 and CA15.3, clinical and pathological criteria of breast cancer, as well as their status during the follow up period after adjuvant therapy. The study consisted of 40 females with newly diagnosed primary breast cancer treated at the Medical Research Institute hospital and 15 healthy females as a control group. Before surgery, big ET-1 serum levels of all breast cancer patients were significantly higher than those of the control group (p0.001). However, after both surgery and adjuvant therapy, big ET-1 was significantly decreased compared to its level before surgery (p<0.001). On the other hand, there was lack of significant differences in the levels of CA15.3, neither before surgery nor after the adjuvant therapy in comparison to the control group. Interestingly, during the follow up period, nine patients developed metastasis to different organs and their serum big ET-1 and CA15.3 levels significantly increased compared to the levels before surgery and after the adjuvant therapy (p0.001, 0.008 and 0.001, 0.008 respectively). Inspite of this observation with this specific group of patients, the use of these markers to predict the development of metastasis during the follow up period cannot be generalized. Furthermore, both of these biochemical parameters showed no correlation to any of the clinicopathological parameters and patients characteristics. Therefore, in conclusion this study found that the testing for serum big ET-1 is more useful than CA15.3 for the diagnosis of breast cancer and future trials will be necessary to establish the importance of big ET-1 as a prognostic marker and to formulate a time-line for its measurement in patients with high risk for developing metastasis.