Elevated tumor-to-liver standardized uptake value ratio (TLR) from preoperative 18F-FDG PET/CT predicts poor prognosis of patients with clear cell renal cell carcinoma after nephrectomy

Abstract

AimTo assess the potential of using preoperative 18F-FDG PET/CT to predict the prognosis of patients with clear cell renal cell carcinoma (ccRCC) after nephrectomy. MethodsSixty-nine patients with newly diagnosed ccRCC who underwent 18F-FDG PET/CT prior to surgery were retrospectively reviewed. The metabolic parameters of maximum standardized uptake value (SUVmax) and tumor-to-liver ratio (TLR) from 18F-FDG PET/CT were obtained. Clinicopathological characteristics, including the World Health Organization/the International Society of Urological Pathology (WHO/ISUP) grade, pathological tumor node metastasis (pTNM) stage, venous tumor thrombus, and so on, were acquired. Univariate and multivariate Cox proportional hazards analyses were performed to identify the prognostic factors for disease-free survival (DFS). ResultsOf the 69 patients, 25 patients (36.2%) experienced disease progression during the follow-up period. In univariate analysis, the primary tumor size (>4.85 cm), pTNM stage (Ⅲ/Ⅳ), WHO/ISUP grade (G3/4), venous tumor thrombus, adjuvant therapy, SUVmax (>3.55), and TLR (>1.66) were found to correlate with the incidence of decreased DFS (P < 0.05). In multivariate analysis, TLR (P = 0.007, HR: 5.489, 95%CI: 1.605-18.774) and pTNM stage (P = 0.024, HR: 10.385, 95%CI: 1.361-79.238) were revealed to serve as independent prognostic predictors for DFS after adjustment for other variables. Only 3 cases (8.3%) with normal TLR showed disease progression, while 22 cases (66.7%) with elevated TLR experienced disease progression. ConclusionccRCC patients with preoperatively elevated TLR (>1.66) and high pTNM stages (Ⅲ/Ⅳ) had significantly unfavorable survival outcomes. These patients should be carefully monitored to detect the possibility of disease progression after nephrectomy as early as possible.