The abortions signal and tocolysis N, Nike Free Run Cr sensitive _4_4. This study involved six cases of breast cancer patients treated with chemotherapy, specifically C. E. F chemotherapeutic agents, comparing the pre-treatment GFR values. The results confirmed a more significant reduction in GFR by 31.64%, indicating glomerular damage, which correlates with an increase in endothelin by 60.47%. However, serum BUN, Cr, and urine levels still remained within the normal range. The examination of GFR in combination with C. E. F chemotherapy drugs has clinical reference value for detecting prompt changes in renal function. Furthermore, combining this with endothelin and urine MG [5,6] can enhance the diagnostic significance of renal function.