[18F]-FDG PET in anal canal cancer: a systematic review and meta-analysis.

ABSTRACT

PURPOSE: To provide comprehensive data on the diagnostic and prognostic value of [18F]-FDG PET (PET) in anal canal cancer patients. METHODS: This study was designed following the PRISMA-DTA guidelines. For the meta-analysis, published original articles (until December 2022) that met the following criteria were included Evaluated PET for locoregional and/or distant disease detection in patients with histopathology-proven anal canal cancer; Compared PET with a valid reference standard; Provided crude data to calculate meta-analytic estimates. Diagnostic measurements from subgroups were calculated in evaluating primary tumour detection, T stage, lymph node and distant metastases. Articles providing prognostic information on PET were also reported as a systematic review. For pooled meta-analytic calculations, the hierarchical method was used. The bivariate model was conducted to find the summary estimates. Analyses were performed using STATA 16. RESULTS: After the screening, 28 studies were eligible to enter the meta-analytic calculations, and data from 15 were reported descriptively. For distinguishing T3/T4 from other T-stages, PET had pooled sensitivity and specificity of 91%(95%CI72%-97%) and 96%(95%CI88%-98%), respectively. The sensitivity and specificity for detecting metastatic (regional and/or distant) disease were 100% (95%CI82%-100%) and 95% (95%CI90%-98%), respectively. For therapy response assessment, the sensitivity and specificity of PET were 96%(95%CI78%-99%) and 86%(95%CI75%-93%), respectively. Higher pre-treatment total metabolic tumour volume was predictive of poorer survival. Conversely, for those achieving complete metabolic response, the 2-year PFS was 94%(95%CI91%-97%) versus 51%(95%CI42%-59%) for others (p-value < 0.001). CONCLUSION: PET may be a useful tool for anal canal cancer therapy planning and provides valuable prognostic information.