Risk factors of renal function after radical nephroureterectomy for upper tract urothelial carcinoma

Objective To investigate the risk factors which can lead to chronic kidney disease (CKD) after radical nephroureterectomy and guide adjuvant chemotherapy for the patients with upper tract urothelial carcinoma (UTUC). Methods 239 patients with UTUC, who were treated at our hospital from October 2010 to February 2015 was analyzed retrospectively. Serum creatinine levels were measured preoperatively and 1 month (range: 21days to 35 days) after radical nephroureterectomy. 129 males and 110 females patients were enrolled. Ages were from 41 to 94, and mean age was 66 years. All patients underwent radical surgery. The pathological stages included Ta/T1/T2/T3/T4, and grades included G1/G2/G3. We calculated GFR using Chronic Kidney Disease Epidemiology Collaboration(CKD-EPI) equations in consideration of age, sex, and serum creatinine level. The new-onset CKD after RNU was defined as when the calculated CKD-EPI GFR decreased to less than 60 ml/(min·1.73 m2). These patients were divided into 2 groups which depended on whether they got CKD after RNU. Cohorts were stratified by gender, age, smoking, BMI, hypertension, diabetes mellitus(DM), tumor location, tumor size, multifocality, pathologic stage, grade, hydronephrosis and preoperative CKD-EPI GFR. The chi-square test was used to examine the relationship among the various cohorts and the CKD after RNU. The Kaplan-Meier method was adopted to identify the relationship between Overall survival (OS). Cancer-specific survival (CSS) and CKD. Univariate and multivariate analyses were performed to study the relationship between clinical factors and CKD after RNU using the Cox proportional hazards regression model and chi-square test. Results In our study, the median follow-up time was 41.3(range from 2-82) months for 239 patients. Median CKD-EPI GFR for all patients before and after surgery was 71.4(65.2-108.7)ml/(min·1.73 m2) and 54.7(37.6-93.8)ml/(min·1.73 m2), meanwhile 105 cases became new-onset CKD. There was no significant difference in overall or cancer specific survival between CKD+ and CKD-(P=0.137, P=0.190). However age (HR=1.825, 95%CI 1.203-2.768, P=0.017), hydronephrosis (HR=0.243, 95%CI 0.106-0.613, P=0.034) and preoperative CKD-EPI GFR(HR=0.237, 95%CI 0.109-0.524, P=0.021) were significantly correlative with postoperative new-onset CKD. Conclusion Age, absence of hydronephrosis and preoperative CKD-EPI GFR were independent risk factors predicting new-onset CKD. They can be the predictor of new-onset CKD. Key words: Upper tract urothelial carcinoma; Radical nephrouretectomy; Chronic kidney disease; Glomerular filtration rate(GFR); Risk factors analysis