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

Abstract

Purpose Prognostic significance of fluorine-18 fluorodeoxyglucose positron emission tomography (18F-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 18F-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 18F-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 18F-FDG-PET parameters could serve as prognostic indicators in anal SCC, but further larger studies are needed in this setting.

Additional Value of 2-[18F]FDG PET/CT Comparing to MRI in Treatment Approach of Anal Cancer Patients

“…It is well-documented that inguinal lymph node involvement, especially bilateral, worsens prognosis in ACa [ 31 , 44 ]. Similarly, in our patients, metabolic lymph node involvement was correlated with recurrence and no response to treatment ( p = 0.006).…”

“…Also, metabolic parameters derived from pre-therapy 2-[ 18 F]FDG PET/CT have been successfully employed for prognostication [ 26 , 27 , 28 ]. However, the intensity of the 2-[ 18 F]FDG uptake on the pre-treatment scan has shown controversial results in inversely corresponding to survival [ 26 , 29 , 30 , 31 ].…”

Evidence-Based PET for Abdominal and Pelvic Tumours

“…Five meta-analyses about 18 F-FDG PET/CT in anal cancer have been included [22][23][24][25][26]. Some meta-analyses evaluated the role in a staging setting, with discordant accuracy values [24][25][26].…”

“…One meta-analysis found a strong prognostic power of 18 F-FDG PET parameters for progression free survival (PFS) and overall survival (OS) [22]. Finally, another meta-analysis assessed the role of 18 F-FDG PET/CT in radiotherapy planning [23].…”

Prognostic Impact of Pretherapeutic FDG-PET in Localized Anal Cancer

“…More than 90% of patients present with locoregional disease at diagnosis and the standard treatment are based on radiochemotherapy [ 6 , 7 , 8 , 9 ]. This therapeutic approach for locally advanced anal SCC has led to a five-year overall survival (OS) ranging from 61% to 85% [ 10 ]. It is therefore important to identify patients who are more likely to have disease recurrence and progression, so that immediate and specific therapies can be implemented at diagnosis in order to obtain a better disease prognosis.…”