Prognostic role of metabolic parameters of ^sup 18^F-FDG PET-CT scan performed during radiation therapy in locally advanced head and neck squamous cell carcinoma

• Published in: European journal of nuclear medicine and molecular imaging Vol. 42; no. 13; p. 1984
• Main Authors: Min, Myo, Lin, Peter, Lee, Mark T, Shon, Ivan Ho, Lin, Michael, stner, Dion, Bray, Victoria, Chicco, Andrew, Tieu, Minh Thi, Fowler, Allan
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer Nature B.V 01.12.2015
• Subjects: Head & neck cancer; Medical imaging; Metabolic disorders; Parameter estimation; Radiation therapy
• ISSN: 1619-7070; 1619-7089
• DOI: 10.1007/s00259-015-3104-8

Purpose To evaluate the prognostic value of ^sup 18^F-FDG PET-CT performed in the third week (iPET) of definitive radiation therapy (RT) in patients with newly diagnosed locally advanced mucosal primary head and neck squamous-cell-carcinoma (MPHNSCC). Methodology Seventy-two patients with MPHNSCC treated with radical RT underwent staging PET-CT and iPET. The maximum standardised uptake value (SUV^sub max^), metabolic tumour volume (MTV) and total lesional glycolysis (TLG) of primary tumour (PT) and index node (IN) [defined as lymph node(s) with highest TLG] were analysed, and results were correlated with loco-regional recurrence-free survival (LRFS), disease-free survival (DFS), metastatic failure-free survival(MFFS) and overall survival (OS), using Kaplan-Meier analysis. Results Optimal cutoffs (OC) were derived from receiver operating characteristic curves: SUV^sub max-PT^=4.25 g/mL, MTV^sub PT^=3.3 cm^sup 3^, TLG^sub PT^=9.4 g, for PT, and SUV^sub max-IN^=4.05 g/mL, MTV^sub IN^=1.85 cm^sup 3^ and TLG^sub IN^=7.95 g for IN. Low metabolic values in iPET for PT below OC were associated with statistically significant better LRFS and DFS. TLG was the best predictor of outcome with 2-year LRFS of 92.7 % vs. 71.1 % [p=0.005, compared with SUV^sub max^ (p=0.03) and MTV (p=0.022)], DFS of 85.9 % vs. 60.8 % [p=0.005, compared with SUV^sub max^ (p=0.025) and MTV (p=0.018)], MFFS of 85.9 % vs. 83.7 % [p=0.488, compared with SUV^sub max^ (p=0.52) and MTV (p=0.436)], and OS of 81.1 % vs. 75.0 % [p=0.279, compared with SUV^sub max^ (p=0.345) and MTV (p=0.512)]. There were no significant associations between the percentage reduction of primary tumour metabolic parameters and outcomes. In patients with nodal disease, metabolic parameters below OC (for both PT and IN) were significantly associated with all oncological outcomes, while TLG was again the best predictor: LRFS of 84.0 % vs. 55.3 % (p=0.017), DFS of 79.4 % vs. 38.6 % (p=0.001), MFFS 86.4 % vs. 68.2 % (p=0.034) and OS 80.4 % vs. 55.7 % (p=0.045). Conclusion The metabolic parameters of iPET can be useful predictors of patient outcome and potentially have a role in adaptive therapy for MPHNSCC. Among the three parameters, TLG was found to be the best prognostic indicator of oncological outcomes.