Comparative Analysis of F-18 FDG PET-Based Metabolic Parameters in the Differential Diagnosis of Esophageal Squamous Cell Carcinoma and Adenocarcinoma

Abstract

Intratumoral heterogeneity is a primary driver of treatment resistance in many malignancies, including esophageal cancer. While Fluorine-18 Fluorodeoxyglucose positron emission tomography/computed tomography (F-18 FDG PET/CT) is a standard tool for staging and response assessment in the esophageal malignancy, the qualitative visual assessment of primary tumor and metastases is limited by interobserver variability. The purpose of this study is to determine if the non-invasive imaging biomarkers on F-18 FDG PET can reliably distinguish the two primary histological subtypes of esophageal malignancy namely squamous cell carcinoma (SCC) and adenocarcinoma (AC).

This is a retrospective study approved by the institutional ethical committee, and conducted in histopathologically proven cases of esophageal malignancy of either squamous cell or AC subtypes, who underwent baseline staging F-18 FDG PET/CT as per the standard guidelines. The metabolic parameters namely tumoral maximum standardized uptake value (SUVmax), total lesional glycolysis (TLG), metabolic tumor volume (MTV) and metabolic ratio of tumor to liver (standardized uptake ratio [SUR]) were calculated and compared between the two histological subtypes using Mann − Whitney U test. A p-value of less than 0.05 was considered statistically significant.

Out of 59 patients (M:F = 33:26) included in the study, 40 had squamous cell subtype and 19 had AC. Median age was 57 years (range: 30–83), and the median SUVmax, SUR, MTV, and TLG of AC group was 10.89 g/mL, 3.86, 9.98 mL, and 55.8 g/mL, while that of squamous group was 13.88 g/mL, 5.6, 13.52 mL, and 108.4 g/mL, respectively. There was significant difference noted in the tumoral SUVmax (p = 0.043), SUR (p = 0.019), and TLG (p = 0.032) between the two groups, with higher metabolic values observed in the squamous group. MTV (p = 0.224) between the two groups was insignificant.

This study demonstrates that quantitative parameters on F-18 FDG PET are effective non-invasive biomarkers for differentiating the histological subtypes of esophageal malignancy. The squamous cell subtype exhibits significantly higher metabolism and total lesion glycolysis than AC.