Radiolabeled choline PET/CT before salvage lymphadenectomy dissection: a systematic review and meta-analysis

To provide a systematic review of recently published reports and carry out a meta-analysis on the use of radiolabeled choline PET/computed tomography (CT) as a guide for salvage lymph node dissection (sLND) in prostate cancer patients with biochemical recurrence after primary treatments. Bibliographic database searches, from 2005 to May 2015, including Pubmed, Web of Science, and TripDatabase, were performed to find studies that included only patients who underwent sLND after radiolabeled choline PET/CT alone or in combination with other imaging modalities. For the qualitative assessment, all studies including the selected population were considered. Conversely, for the quantitative assessment, articles were included only if absolute numbers of true positive, true negative, false positive, and false negative test results were available or derivable from the text for lymph node metastases. Reviews, clinical reports, and editorial articles were excluded from analyses. Eighteen studies fulfilled the inclusion criteria and were assessed qualitatively. A total of 750 patients underwent radiolabeled choline (such as C-choline or F-choline) PET/CT before sLND. A quantitative evaluation was performed in nine studies. A patient-based, a lesion-based, and a site-based analysis was carried out in nine, four, and five studies, respectively. The pooled sensitivities were 85.3% [95% confidence interval (CI)78.5–90.3%], 56.2% (95% CI41.6–69.7%), 75.3% (95% CI56.6–87.7%), and 63.7% (95% CI41–81.6%), respectively, for patient-based, lesion-based, pelvic site-based, and retroperitoneal site-based analysis. The pooled positive predictive values (PPVs) were 75% (95% CI68–80.9%), 85.8% (95% CI66.8–94.8%), 81.2% (95% CI70.1–88.9%), and 75.2% (95% CI58.7–86.7%), respectively, in the same analyses. High heterogeneities among the studies were found for sensitivities and PPVs ranging between 61.7–93.3% and 60.6–94.5%, respectively. Radiolabeled choline PET/CT has only a moderate sensitivity for the detection of metastatic lymph nodes in patients who are candidates for sLND, although the pooled PPVs ranged between 75 and 85.8% for all type of subanalyses. The presence of high heterogeneity among the studies should be considered carefully.