Role of 18F-FDG PET/CT for detection of recurrence and metastases in renal cell carcinoma—are we underusing PET/CT?

Abstract

The aim of this study was to compare 18 F-fluorodeoxyglucose positron emission tomographycomputed tomography ( 18 F-FDG PET/CT) scan with computed tomography (CT) scan for detecting recurrence and metastasis in renal cell carcinoma patients. METHODSThis retrospective study included patients from October 2013 to April 2017. Contrast-enhanced CT and PET/CT scans were compared and correlated with histopathology or/and follow-up studies. RESULTSSeventy-six patients, 60 males, were included. Lesions included primary renal, recurrent renal fossa lesions, lymph nodes, and distant metastatic lesions. Of 176 malignant lesions, CT detected 157 lesions; of which, 154 were true positive. Twenty-two false-negative lesions showed abnormal FDG uptake. CT scan had positive predictive value (PPV), negative predictive value (NPV), sensitivity, specificity, and accuracy of 98.0%, 37.1%, 87.5%, 81.2%, and 86.9%, respectively. All 176 lesions were PET/CT-positive. PET/CT had PPV, NPV, sensitivity, specificity, and accuracy of 100% each. The specificity and NPV of PET/CT were superior (P < .05). CONCLUSIONPET/CT appears more accurate than CT scan for detecting metastasis and recurrence in renal cell carcinoma patients. R enal cell carcinoma (RCC) is the most common solid kidney cancer. The incidence in Asian population is 1.1-6.0/100 000. World over, the 5-year survival rate is 68.4%. 1 Localized RCC patients treated surgically usually have favorable outcomes. However, about 20%-40% patients later develop distant metastases. The main aim of postoperative follow-up is early detection of local recurrence and/or distant metastases. Post-surgery follow-up imaging is commonly done with conventional imaging modalities (CIM), mainly computerized tomography (CT) scan. These have certain limitations in assessing local recurrence due to postoperative changes such as fibrosis, adjacent organs occupying the space of the renal fossa, the presence of surgical clips causing metallic artifacts, and other such changes.About one-fourth of the patients are found to be metastatic at initial presentation, with very few (<5%) having single-site metastasis. 2