Predictive value of quantitative metabolic tumor volume and metabolic index analysis in lung cancer stereotactic radiotherapy with F-18 FDG PET/CT.

Objective: The objective of this study was to investigate predictive value of quantitative metabolic tumor volume and metabolic index analysis in lung cancer stereotactic radiotherapy with F-18 FDG PET/CT.

Patients And Methods: Overall, 94 early-stage non-small cell lung cancer (NSCLC) patients who were administered stereotactic radiotherapy were included in the study.

Results: Most of the study patients were male (91.5%). Mean age of the patients was 68.5 ± 9.0 years. The primary lung tumor was located centrally and peripherally in 25 (26.6%) and 69 (73.4%) of the patients, respectively. The median gross tumor volume (GTV) was 16.2 cc [interquartile range (IQR): 7.1-32.9]. Whereas all patients who had peripheral tumors survived, 17 patients with central tumors (70.8%) died during the study period (p = 0.001). Biologically effective dose (BED10) values were significantly higher in patients who had peripheral tumors compared with patients with central tumors (p = 0.001). Significantly more patients died in patients who had BED values below 100 Gy compared to patients who had BED values over 100 Gy (p = 0.001). The survival distributions for the two groups were significantly different (p < 0.001). Only GTV and Pretreatment SUVmean appeared as significant predictors of mortality. BED10 values showed a significant and strong positive correlation with total radiation dose, whereas it showed a significant strong negative correlation with number of fractions.

Conclusions: The use of repeated 18F-FDG PET to assess survival early during stereotactic radiotherapy is possible in patients with early-stage non-small cell lung cancer. A decrease in GTV and pretreatment SUVmean according to F-18 FDG PET/CT uptake by the primary tumor correlates with survival.