Nowadays, it is necessary to explore effective biomarkers associated with tumor immune microenvironment (TIME) noninvasively. Here, we investigated whether the metabolic parameter from preoperative 2-[18F]FDG PET/CT could provide information related to TIME in patients with clear cell renal cell carcinoma (ccRCC).
Ninety patients with newly diagnosed ccRCC who underwent 2-[18F]FDG PET/CT prior to surgery were retrospectively reviewed. The immunological features included tumor-infiltrating lymphocytes (TILs) density, programmed death-ligand 1 (PD-L1) expression, and tumor immune microenvironment types (TIMTs). TIMTs were classified as TIMT I (positive PD-L1 and high TILs), TIMT II (negative PD-L1 and low TILs), TIMT III (positive PD-L1 and low TILs), and TIMT IV (negative PD-L1 and high TILs). The relationship between maximum standardized uptake value (SUVmax) in the primary lesion from 2-[18F]FDG PET/CT and immunological features was analyzed. Cox proportional hazards analyses were performed to identify the prognostic factors for disease-free survival (DFS) after nephrectomy.
Tumors with high TILs infiltration showed remarkable correlation with elevated SUVmax and aggressive clinicopathological characteristics, such as high World Health Organization/International Society of Urological Pathology (WHO/ISUP) grade. PD-L1 expression on tumor cells was positively associated with WHO/ISUP grade and negatively correlated with body mass index (BMI). However, no correlation was observed between SUVmax and PD-L1 expression, regardless of its spatial tissue distribution. SUVmax of TIMT I and IV was higher than that of TIMT II, but there was remarkable difference merely between TIMT II and IV. In multivariate analysis, SUVmax (P = 0.022, HR 3.120, 95% CI 1.175-8.284) and WHO/ISUP grade (P = 0.046, HR 2.613, 95% CI 1.017-6.710) were the significant prognostic factors for DFS. Six cases (16.2%) with normal SUVmax showed disease progression, while 25 cases (71.4%) with elevated SUVmax experienced disease progression. Conversely, the immunological features held no prognostic value.
Our findings demonstrated that 2-[18F]FDG PET/CT could provide metabolic information of TIME for ccRCC patients and develop image-guided therapeutic strategies accordingly. Patients with elevated preoperative SUVmax should be seriously considered, and perioperative immunotherapy might be beneficial for them.
European journal of nuclear medicine and molecular imaging. 2021 May 12 [Epub ahead of print]
Caixia Wu, Yonggang Cui, Jumei Liu, Linlin Ma, Yan Xiong, Yanqing Gong, Yanyan Zhao, Xi Zhang, Silu Chen, Qun He, Jianhua Zhang, Meng Liu, Yan Fan
Department of Nuclear Medicine, Peking University First Hospital, Beijing, 100034, China., Department of Pathology, Peking University First Hospital, Beijing, 100034, China., Department of Urology, Peking University First Hospital, Institute of Urology, Peking University, National Urological Cancer Center, Beijing, 100034, China., Department of Nuclear Medicine, Peking University First Hospital, Beijing, 100034, China. ., Department of Nuclear Medicine, Peking University First Hospital, Beijing, 100034, China. .