The Utility of F-FDG-PET-CT Metabolic Parameters in Evaluating the Primary Tumor Aggressiveness and Lymph Node Metastasis of Nasopharyngeal Carcinoma.

Background: Following changes in primary tumor (T) and lymph node (N) staging for nasopharyngeal carcinoma (NPC) in the , simplification of T staging has been proposed. However, a limited range of 2-deoxy-2-[fluorine-18] fluoro-D-glucose positron emission tomography-computed tomography (F-FDG PET-CT) metabolic parameters has been investigated. Therefore, we aimed to evaluate the primary tumor invasiveness and the lymph node metastasis (LNM) of NPC from a metabolic perspective.

Methods: A total of 435 NPC patients underwent F-FDG PET/CT before treatment were retrospectively examined. The primary endpoint was differences in standard uptake value (SUV), lean body mass-normalized SUV (SUL), body surface area-normalized SUV (SUS), glucose-normalized SUV (GN), metabolic tumor volume (MTV), total lesion glycolysis (TLG), and glucose-normalized total lesion glycolysis (GNTLG) of primary tumors and LNM between different T and N stages. The metabolic parameters associated with T and N staging were identified.

Results: There were significant differences between all parameters relative to the primary tumor but no significant differences in any parameter relative to the LNM and T stages. Higher mean values of TGN, TGN, TSUV, and TSUS were associated with advanced T stages. Higher mean values of all the LNM parameters were associated with more advanced N stages. Only primary tumor metabolic tumor volume (TMTV), TSUV, TSUL, and TSUS showed a significant positive association with T staging, while lymph node metabolic tumor volume (LNMTV) and TSUS were significantly positive in N staging.

Conclusions: Our findings suggest that metabolic parameters are useful indicators of tumor invasiveness and LNM based on the Eighth Edition manual. Compared with volume-dependent parameters, TGN, TGN, TSUV, and TSUS may be better indicators of local tumor aggressiveness. SUS of the primary tumor was associated with LNM. In addition to SUV, other metabolic parameters (eg, SUL, SUS, GN, and GN) could evaluate tumor aggressiveness and LNM better.