Tumor heterogeneity, hypoxia, and immune markers in surgically resected non-small-cell lung cancer

This study aimed to determine the prognostic role of textural features and their association with metabolic parameters, hypoxia, and cancer-related immune markers in non-small-cell lung cancer (NSCLC) patients.

The trial was registered at http://www.clinicaltrials.gov (NCT02519062). From January 2010 to May 2014, 44 patients (male : female=33 : 11; median age: 69.5 years), referred to our Institution for NSCLC resection, were enrolled. Tumor specimens were assessed for HIF-1α, CD68-TAMs, CD8-TILs, PD-1-TILs, and PD-L1 expressions. All patients underwent fluorine-18-fluorodeoxyglucose (F-FDG) PET before surgery. Semiquantitative parameters included maximum standardized uptake value (SUVmax), SUVpeak, SUVmean, metabolic tumor volume, and total lesion glycolysis, whereas for heterogeneity, we considered tumor sphericity, skewness, kurtosis, entropy, and energy. Parameters were correlated with disease-free survival (DFS) considering a median follow-up of 22.7 months.

SUVmax (cutoff: 7.9; P=0.015), SUVpeak (cutoff: 6.7; P=0.013), SUVmean (cutoff: 5.5; P=0.028), metabolic tumor volume (cutoff: 3.6 cm; P=0.027), and entropy (cutoff: 1.89; P=0.045) showed a statistically significant association with DFS. Also, a high expression of cytoplasmic HIF-1α (score 3) was associated with DFS (hazard ratio: 0.09; P=0.003). All F-FDG PET variables differed significantly in tumors with high or low entropy (≤1.89). Also, a significantly higher level of mean CD8-TILs was observed in tumors with higher entropy (P=0.041).Using identified prognostic factors, we developed a scoring system, which was confirmed to be associated with DFS (P<0.004). On receiver operating characteristics analysis, a score above 3 was defined as the optimal cutoff point.

Tumor heterogeneity, metabolic parameters, and high expression of hypoxia were found to be prognostic factors in NSCLC patients who were candidates for surgery. Higher levels of entropy appear to be associated with increased density of CD8-TILs. The combination of investigated prognostic factors enabled the development of a potential scoring system associated with DFS.