Prognostic value of preoperative metabolic tumor volume and total lesion glycolysis measured by 18F-FDG PET/CT in salivary gland carcinomas

Abstract

Metabolic tumor volume (MTV) and total lesion glycolysis (TLG) from (18)F-FDG PET/CT are emerging prognostic biomarkers in various human cancers. This study examined the prognostic value of these metabolic tumor parameters measured by pretreatment (18)F-FDG PET/CT in patients with salivary gland carcinomas.

Methods: Forty-nine patients with intermediate- or high-grade salivary gland carcinomas who underwent definitive surgery with or without radiotherapy or chemoradiotherapy were evaluated preoperatively by (18)F-FDG PET/CT. Maximum standardized uptake values (SUV max), MTV, and TLG were measured for each patient. Univariate and multivariate analyses were used to identify clinicopathologic and imaging variables associated with progression-free survival (PFS) and overall survival (OS). Univariate analyses included the following variables: age, sex, pT and pN classifications, overall pTNM stage, histologic grade, resection margin, tumor lymphovascular invasion and perineural invasion, postoperative adjuvant therapy, gross total volume, SUV max, MTV, and TLG.

Results: The 3-y PFS and OS rates for all study patients were 66.9% and 81.6%, respectively. The median SUV max, MTV, and TLG were 5.1 (range, 1.7-21.5), 16.2 mL (1.0-115.1 mL), and 24.4 g (2.1-224.4 g), respectively. Univariate analyses showed that there were significant correlations between pT classification, pN classification, MTV, and TLG and both PFS and OS (P < 0.05). However, SUV max was not associated with either PFS (P = 0.111) or OS (P = 0.316). Multivariate analyses revealed that MTV (P = 0.011; hazard ratio, 11.50; 95% confidence interval, 1.45-91.01) and TLG (P = 0.038; hazard ratio, 3.55; 95% confidence interval, 1.07-11.76) were independent variables for PFS.

Conclusion: Pretreatment values of MTV and TLG are independent prognostic factors in patients with intermediate or high-grade salivary gland carcinomas.

Keywords: 18F-FDG PET/CT; metabolic tumor volume; prognostic factors; salivary gland carcinomas; total lesion glycolysis.