Introduction

Fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT) is useful for detecting of primary lesion and metastasis in patients with upper urinary tract urothelial carcinoma (UTUC). However, there is no study about ipsilateral hydronephrosis on FDG-PET/CT in patients with UTUC. We aimed to evaluate the value of our classification of hydronephrosis on FDG-PET/CT to predict postoperative renal function and pathological outcomes.

Methods

We retrospectively reviewed patients treated with nephroureterectomy (NU) for UTUC at our institution from 2010 to 2016. Among them, 71 patients were examined by FDG-PET/CT before NU. Patients treated with ureteral stent or nephrostomy at the time of FDG-PET/CT scan were excluded, leaving 64 patients for analysis. We classified the hydronephrosis on FDG-PET/CT based on the renal FDG excretion as follows: type0 : no hydronephrosis ; type1 : hydronephrosis with FDG accumulation ; type2 : hydronephrosis without FDG accumulation. Estimated glomerular filtration rate (eGFR [ml/min/1.73m²]) was calculated before the treatment and at early (within 1 month) and late (3-6 months) time points after NU. The change of eGFR was calculated at early time point after NU compared to pretreatment eGFR. The renal dysfunction event, defined as new-onset stage3 chronic kidney disease (CKD) or worsening of CKD stage, was evaluated at late time point after NU compared to pretreatment eGFR. SPSS was used for statistical analysis.

Results

The patients of type 0, 1, 2 were 30 (47%), 18 (28%) and 16 (25%), respectively. The median change of eGFR in type 0, 1, 2 was -23.9, -19.4 and 2.4 ml/min/1.73m², respectively. The renal dysfunction event rate was the lowest in type2 group (86, 63 vs 19%). On multivariate analysis, classification of hydronephrosis and preoperative eGFR were associated with renal dysfunction event (p<0.05). Furthermore, type2 hydronephrosis was significantly associated with pahological grade3, LVI+ , ≥pT2 (muscle invasive cancer) and pN+ (p<0.05). On multivariate analysis, type2 hydronephrosis was associated with muscle invasive UTUC (p<0.05).

Conclusions

We classified the hydronephrosis based on renal FDG excretion. The classification of pretreatment hydronephrosis on FDG-PET/CT is simple and useful for predicting postoperative renal function and worse pathological outcomes in patients with UTUC.

Funding

none