Prognostic Significance of Fluorine-18 Fluorodeoxyglucose Positron Emission Tomography in Anal Squamous Cell Carcinoma: A Systematic Review and a Meta-Analysis.

Purpose: Prognostic significance of fluorine-18 fluorodeoxyglucose positron emission tomography (18 F-FDG-PET) in anal squamous cell carcinoma (SCC) has been evaluated in several studies; however, the results seem to be controversial and no consensus exists about its predictive capability. The current meta-analysis was carried out to comprehensively investigate the prognostic significance of 18 F-FDG-PET parameters in patients with anal SCC.

Methods: A comprehensive literature search of PubMed/MEDLINE and Scopus databases was performed to retrieve pertinent articles published until August 5th 2018, concerning the prognostic significance of 18 F-FDG-PET in patients with anal SCC. No language restriction was used. Several prognostic factors were reported for progression-free survival (PFS) and overall survival (OS) including pretreatment maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), inguinal nodal uptake, and metabolic response to therapy.

Results: Eleven studies (741 patients) were included. The pooled hazard ratio (HR) for the probability of PFS was 5.36 (95% confidence interval (95% CI): 3.12-9.21, p < 0.001) for metabolic response to therapy and 1.98 (95% CI: 1.26-3.12, p =0.003) for SUVmax. The pooled HR for the probability of OS was 5.87 (3.02-11.39, p < 0.0001) for metabolic response to therapy. On the other hand, the study revealed that the pooled HRs of MTV and inguinal nodal uptake for PFS were 1.56 (95% CI: 0.96-2.53, p =0.072) and 1.79 (95% CI: 1-3.21, p =0.051), respectively.

Conclusions: Our findings propose that some 18 F-FDG-PET parameters could serve as prognostic indicators in anal SCC, but further larger studies are needed in this setting.