Monitoring the estimated glomerular filtration rate (eGFR) in patients with small-cell lung cancer during chemotherapy: equations based on serum creatinine or cystatin C?

Background: This study compared the differences between the estimated glomerular filtration rate (eGFR) calculated by several equations based on serum creatinine (Scr) and cystatin C (CysC) concentrations for monitoring renal function in patients with small-cell lung cancer (SCLC) during chemotherapy.
Methods: Seventy-one patients with SCLC were retrospectively analyzed. The eGFR before and after each chemotherapy cycle was calculated by the following equations: the chronic kidney disease epidemiology collaboration (CKD-EPI) equation, the modification of diet in renal disease (MDRD) equation, the Cockcroft-Gault (CG) equation, and five CysC-based equations. The patients were compared among the different eGFR groups.
Results: The mean decreases in eGFR _CKD-EPI (-2.25 ± 9.89 ml/min/1.73 m ² ) between each treatment cycle were more significant than the decreases in eGFR _CG (-0.46 ± 10.17 ml/min/1.73 m ² ), eGFR _MDRD (-0.48 ± 9.79 ml/min/1.73 m ² ), and five calculated eGFR _CysC (p < 0.05). Single-/multiparameter analyses showed that patients with a higher body mass index (BMI >23) and receiving more treatment cycles (>3) were at increased risk for developing renal impairment with an eGFR less than 60 ml/min/1.73 m ² during chemotherapy.
Conclusions: The eGFR calculated by the CKD-EPI equation changed more significantly between each chemotherapy cycle than did the eGFR from the other equations based on Scr or CysC in patients with SCLC. Oncologists should pay more attention to the renal function of specific patient groups during treatment.