In a pooled analysis reported in the Journal of Clinical Oncology, Michel Meignan, MD, PhD, of the Université Paris-Est Créteil, and colleagues found that higher baseline total metabolic tumor volume measured by 18F-fluorodeoxyglucose (18F-FDG) positron-emission tomography–computed tomography (FDG PET-CT) was associated with poorer outcome in patients with high tumor burden follicular lymphoma.
The analysis included 185 patients receiving immunochemotherapy in 3 multicenter trials. Total metabolic tumor volume was computed using the 41% maximum standardized uptake value threshold method. Patients had a median age of 55 years, 92% had stage III to IV disease, 37% had a Follicular Lymphoma International Prognostic Index (FLIPI) score of 3 to 5, and 31% had a FLIPI2 score of 3 to 5.
Total Metabolic Tumor Volume and Outcome
Median follow-up was 64 months. Among all patients, 5-year progression-free survival was 55%, and overall survival was 92%. The median total metabolic tumor volume was 297 cm3. Optimal cutoff was identified as 510 cm3, with survival being poorer in the 29% of patients with total metabolic tumor volume > 510 cm3. For higher vs lower total metabolic tumor volume, 5-year progression-free survival was 33% vs 65% (hazard ratio [HR] = 2.90, P < .001), and 5-year overall survival was 85% vs 95% (HR = 3.45, P = .010).
Total Metabolic Tumor Volume and FLIPI2
On multivariate analysis, total metabolic tumor volume (HR = 2.3, P = .002) and FLIPI2 score (HR = 2.2, P = .002) were independent predictors of progression-free survival. Use of these 2 factors together identified risk groups with 5-year progression-free survival of 20% (high total metabolic tumor volume and intermediate-to-high FLIPI2 score; HR = 5.0, P < .001), 46% (high total metabolic tumor volume or intermediate-to-high FLIPI2; HR = 2.1, P = .007), and 69% (low total metabolic tumor volume and low FLIPI2).
The investigators concluded: “Baseline [total metabolic tumor volume] is a strong independent predictor of outcome in [follicular lymphoma]. In combination with FLIPI2 score, it identifies patients at high risk of early progression. It warrants further validation as a biomarker for development of first-line PET-adapted approaches in [follicular lymphoma].”