Prognostic Value of Lymph Node to Primary Tumor Standardized Uptake Value Ratio in Esophageal Cancer

Abstract

Esophageal cancer harbors high mortality rate despite current standard concurrent chemoradiotherapy followed by operation. Thus, further stratification of the patients may offer better therapeutic outcome to those having a favorable nature of disease. We presume the lymph node to primary tumor standardized uptake value (SUVmax) ratio (NTR) in 18F-FDG PET/CT may provide further prognostic information. The patients with non-metastatic and unresectable esophageal cancer receiving 18F-FDG PET/CT staging and treated by chemoradiotherapy were retrospectively reviewed. The SUVmax of the metastatic lymph nodes and the primary tumor were collected and NTR was calculated. Receiver operating characteristic (ROC) analysis was performed to determine the optimal cut-off value for NTR. Kaplan-Meier method and Cox proportional hazard model were used for overall survival (OS), progression-free survival (PFS), distant metastasis-free survival (DMFS) analysis. From 2009 to 2016, 96 eligible patients were collected and analyzed. The median follow-up time was 9.72 months (1.6 to 82.6 months). The median OS was significantly higher (18.3 vs. 9.2 months, p = 0.009) in the group with NTR lower than 0.64. A significantly better median PFS (9.2 vs. 5.9 months, p = 0.022) and DMFS (31.2 vs. 9.5 months, p = 0.002) were also found in the groups with lower NTR (using 0.42 and 0.46 as cut-off values respectively). Multivariable analysis revealed that NTR was an independent prognostic factor for OS (hazard ratio [HR] 2.24, p = 0.039) and DMFS (HR 2.84, p = 0.009). High pretreatment NTR predicts worse treatment outcomes for patients with non-metastatic and unresectable esophageal cancer.