Pre-treatment metabolic tumor volume predicts tumor metastasis and progression in high-grade salivary gland carcinoma.

Abstract

High-grade salivary gland carcinoma (SGC) shows a high rate of metastasis and post-treatment recurrence, resulting in poor patient survival. Therefore, we evaluated the utility of pre-treatment 18F-FDG PET/CT parameters in predicting metastasis, tumor progression, and survival of high-grade SGC patients. This observational study included 75 patients with previously untreated high-grade SGC who underwent pre-treatment 18F-FDG PET/CT scanning and subsequent treatment. Standardized uptake values (SUV), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) were measured on pre-treatment 18F-FDG PET/CT. Logistic regression analysis was used to identify the relationship of these factors with metastasis. Cox proportional hazard regression analyses were used to identify associations between PET parameters and both progression-free survival (PFS) and overall survival (OS). A total of 36 (48%) patients had neck or distant metastases at initial staging. After controlling for clinical factors, MTV (> 8.8mL) was an independent factor for initial metastasis (adjusted odds ratio 4.80, 95% confidence interval 1.09-21.20; P = 0.039). All PET parameters of SUVmax (> 4.3), SUVmean (> 3.0), SUVpeak (3.9), MTV (> 8.8mL), and TLG (> 31.1g) were significant variables for PFS (all P < 0.05), while MTV and TLG were significant factors for OS. After controlling for clinicopathological factors, MTV (adjusted hazard ratio 4.36, 95% confidence interval 1.69-11.26; P = 0.002) and TLG (3.41, 1.47-7.91; P = 0.004) were significantly associated with PFS, but not OS. MTV is useful among quantitative PET measurements for predicting initial metastasis and PFS in patients with high-grade SGC.