The role of PET/CT in the evaluation of patients with urothelial cancer: a systematic review and meta-analysis

Purpose The aim of our systematic review and meta-analysis is to define the role of PET/CT in the evaluation of patients with urothelial cancer (UC). Methods Searches of the major scientific literature databases were carried out to select English language articles dealing with PET and UC. Only original articles concerning UC patients who were (1) candidates for radical surgery, (2) restaged for suspicions of recurrences or metastasis and (3) evaluated after treatments were selected and included in the present study. Abstract, reviews, clinical cases and editor comments were excluded. Moreover, articles on the optimization of PET/CT study protocol, such as refilling, diuretic administration or similar, were excluded. Only studies that met the following criteria were included in the meta-analysis: sample size equal to/greater than 15 patients; index test: 18F-FDG PET/CT; standard of reference for the identification of disease; outcomes, such as true positive, true negative, false positive and false negative, which allowed us to construct 2 x 2 contingency tables. Results Thirty-three papers were collected and analyzed. The studies included a total of 1944 patients, of which 1661 patients were assessed at initial staging and 283 in the restaging phase. 18F-FDG was the most employed tracer for the evaluation of UC patients (29 out of 33 studies), while 11C-choline and 11C-acetate were employed alone or in concomitance in three and one articles, respectively. The pooled sensitivities and specificities of 18F-FDG PET/CT were 41.8% (95% CI 41.1-52.5), 91% (95% CI 88.2-93.3), 94% (95% CI 88.6-97.4) and 93% (95% CI 84.3-97.7), respectively, for lymph node involvement at the initial staging and in the restaging phase. Both in initial staging and in restaging, 18F-FDG PET/CT was more accurate than conventional imaging (i.e., CT and/or MRI). Conclusions 18F-FDG PET/CT is more accurate than conventional imaging for the evaluation of patients with UCs, both in the staging and in the restaging setting. In this latter phase, 18F-FDG PET/CT has a high pooled diagnostic performance. A multicenter study should be drawn to demonstrate how PET/CT imaging is useful in the diagnostic pathway of patients with UCs.