Prognostic value of metabolic tumor volume and total lesion glycolysis from ¹⁸F-FDG PET/CT in patients undergoing stereotactic body radiation therapy for stage i non-small-cell lung cancer

OBJECTIVES: The aim of this study was to evaluate the prognostic value of pretreatment F-fluorodeoxyglucose PET/computed tomography (CT), particularly in the assessment of metabolic tumor burden markers such as metabolic tumor volume (MTV) and total lesion glycolysis (TLG), with respect to clinical outcomes in stage I non-small-cell lung cancer (NSCLC) patients undergoing stereotactic body radiation therapy (SBRT). METHODS: This retrospective study evaluated 50 patients who underwent SBRT for stage I NSCLC from May 2007 to December 2012. The maximum standardized uptake value (SUV_max), average SUV (SUV _avg), MTV, and TLG were measured from the PET/CT scan. The study population was dichotomized at the median into high and low groups. Kaplan-Meier log-rank tests were then used to compare high with low PET/CT parameter groups, and univariate Cox proportional hazards regression analysis was carried out to identify predictors of overall survival. RESULTS: The 2-year local control rate was 93.7%. After a median follow-up of 25.1 months, the 2-year overall survival was 79.3%. Eight patients (16%) had disease recurrence. There were three local failures (6%), three mediastinal failures (6%), and six cases of distant metastases (12%). Both Kaplan-Meier actuarial analysis and Cox proportional hazards regression found no correlation between SUV_max, SUV _avg, MTV, and TLG and overall survival. CONCLUSION: Standard PET/CT measures, such as SUV_max, as well as newer measures of metabolic tumor burden, such as MTV and TLG, were not correlated with overall survival in our study population of stage I NSCLC patients undergoing SBRT. Larger studies with longer follow-up periods are needed to confirm these results.