FDG PET/CT as a prognostic biomarker in the era of molecular-targeting therapies: max SUVmax predicts survival of patients with advanced renal cell carcinoma.

Noboru Nakaigawa,Hisashi Hasumi,Ukihide Tateishi,Ichiro Ikeda,Tomohiro Kaneta,Keiichi Kondo,Kazuhiro Namura,Daiki Ueno,Ryogo Minamimoto,Kazuhide Makiyama,Takeshi Kishida,Tomio Inoue,Masahiro Yao,Yoshinobu Kubota,Kazuki Kobayashi

doi:10.1186/s12885-016-2097-4

Abstract

BackgroundVarious molecular-targeting therapies have become available for the treatment of advanced renal cell carcinoma (RCC). Accurate prognostication is desirable for choosing the appropriate treatment for individual patients. 18F-2-fluoro-2-deoxyglucose positron-emission tomography/computed tomography (FDG PET/CT) is a non-invasive tool for evaluating glucose accumulation, which can be an index of biological characteristics of cancer. We prospectively evaluated FDG PET/CT as a prognostic indicator in patients with advanced RCC.MethodsA total of 101 patients slated for different systematic therapies for advanced RCC were enrolled between 2008 and 2014. A total of 61 patients had recurrent RCC (58 metastatic and 3 regional) and 40 patients had stage IV RCC (36 metastatic and 4 locoregional). Sixteen patients had not undergone nephrectomy. Pre-treatment FDG PET/CT was performed, and the max SUVmax (the highest SUV measurement in each patient) was recorded. The max SUVmax was compared with different clinical risk factors as prognostic indicators. The median observation period was 18 months (range 1–70 months).ResultsThe max SUVmax of the 101 subjects ranged from undetectable to 23.0 (median 6.9). Patients with high max SUVmax had a poor prognosis. Multivariate analysis with standard risk factors revealed that max SUVmax was an independent predictor of survival (p < 0.001; hazard ratio 1.265; 95 % confidence interval 1.159–1.380). A cutoff of 8.8 for max SUVmax advocated in our previous report was highly significant (p < 0.0001). When we subclassified the max SUVmax values, the median overall survival of subjects with max SUVmax < 7.0 was 41.9 months. That of subjects with max SUVmax between 7.0 and 12.0 was 20.6 months. That of subjects with max SUVmax ≥ 12.0 was 4.2 months. The differences were statistically significant.ConclusionsPretreatment max SUVmax assessed by FDG PET/CT is a useful prognostic marker for patients with advanced RCC, providing helpful information for clinical decision making.

Highlights

Various molecular-targeting therapies have become available for the treatment of advanced renal cell carcinoma (RCC)
We focused on standardized uptake value (SUV), a quantitative simplified measure of tissue FDG accumulation, and previously reported that max SUVmax predicted the overall survival (OS) of patients with advanced RCC [13]
Nine were eventually eliminated: four whose pathology could not be confirmed conclusively, three who decided against treatment after evaluation by FDG PET/ CT, one patient had a fasting blood sugar over 150 mg/dL, and one with contralateral kidney metastases for which accurate SUV could not be measured owing to the urinary excretion of the radiotracer

Summary

Introduction

Various molecular-targeting therapies have become available for the treatment of advanced renal cell carcinoma (RCC). With elucidation of the oncogenic mechanisms of RCC, agents that target critical molecules in the biological pathways necessary for oncogenesis, such as vascular endothelial cell growth factor or the mammalian target of rapamycin (mTOR), have been developed These molecular-targeting therapeutics have improved outcomes for patients with advanced RCC [6,7,8,9], and are recommended as the main treatments for advanced RCC in clinical guidelines applied worldwide [10, 11]. The Memorial Sloan-Kettering Cancer Center (MSKCC) classification using five clinical factors including performance status, the interval from diagnosis to start of treatment, lactate dehydrogenase (LDH), corrected calcium, and anemia, is most commonly used for prognosis [12] These clinical parameters are thought to express the biological activity of RCC indirectly. In this era of molecular-targeting therapy, an index that expresses the biological activity of RCC directly, and prognosticates accurately, is desired for appropriate clinical decision making

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