Intratherapy or posttherapy FDG PET or FDG PET/CT for patients with head and neck cancer: A Systematic review and metaanalysis of prognostic studies

OBJECTIVE. The objective of this study was to determine the predictive value of intratherapy or posttherapy FDG PET or FDG PET/CT with regard to overall survival (OS) and event-free survival (EFS) outcomes for patients with head and neck cancer (HNC). MATERIALS AND METHODS. A systematic search of the MEDLINE and EMBASE databases was performed. Studies in which PET/CT was performed during or after completion of primary therapy and for which survival outcomes were reported were included. OS and EFS were considered as outcomes. The pooled estimates of hazard ratios (HRs) and Mantel- Haenszel risk ratios (RRs) were generated for summary effects. RESULTS. Twenty-six studies were eligible for inclusion. The pooled HRs for OS (nine studies, 600 patients) and EFS (eight studies, 479 patients) were 3.55 (95% CI, 2.35-5.37) and 4.73 (95% CI, 2.61-8.56), respectively. Results from the RR analyses, including all 26 studies, showed that intratherapy or posttherapy PET/CT could significantly predict the 2-year and 3- to 5-year risk of death or disease progression. A positive PET result was associated with a more-than-sixfold increase in the risk of death within 2 years (2-year RR, 6.19 [95% CI, 3.04- 12.62]), which is attenuated-but remains significant-with longer follow-up (3- to 5-year RR, 2.42 [95% CI, 1.76-3.32]). The estimated pooled RRs for 2-year mortality were 8.31 (95% CI, 3.83-18.01) for posttherapy PET/CT versus 3.99 (95% CI, 1.43-11.10) for intratherapy PET/CT. CONCLUSION. Positive results of intratherapy or posttherapy PET/CT examinations strongly predict the risk of adverse events and death, particularly within 2 years but also up to 5 years, for patients with HNC.