Glucose metabolism assessed by fluorodeoxyglucose positron emission tomography and response to chemoimmunotherapy in esophageal squamous cell carcinoma: An exploratory analysis.

INTRODUCTION: Tumor glucose metabolism, as assessed by fluorodeoxyglucose positron emission tomography (FDG-PET), can reflect both intrinsic tumor biology and the host systemic condition. Increased FDG uptake has been linked to aggressive tumor behavior, altered metabolic activity, and a distinct tumor microenvironment. However, its clinical relevance remains unclear in patients with unresectable or recurrent esophageal squamous cell carcinoma (ESCC) treated with chemoimmunotherapy. METHODS: We retrospectively analyzed 47 patients treated with fluorouracil plus cisplatin-based chemoimmunotherapy. FDG-PET was performed before treatment initiation, and maximum standardized uptake value (SUVmax) was used to assess tumor glucose metabolism. Treatment response was evaluated according to the Response Evaluation Criteria in Solid Tumors, and overall survival (OS) was calculated from the start of treatment. Patients were classified using an exploratory data-derived SUVmax cutoff value of 17.55, and treatment response, survival, and baseline characteristics were compared between groups. Continuous SUVmax was also analyzed using Cox models. RESULTS: Patients with high SUVmax showed a significantly higher response rate than those with low SUVmax (83.3% vs. 52.6%, p = 0.0462). Higher SUVmax was independently associated with shorter OS (adjusted HR per unit, 1.105; 95% CI, 1.008-1.213; p = 0.0320). CONCLUSION: Higher pretreatment SUVmax was associated with a higher response rate but poorer OSin patients with unresectable or recurrent ESCC receiving chemoimmunotherapy. SUVmax may reflect both treatment sensitivity and aggressive tumor biology and may provide clinically relevant information on treatment response and prognosis, although the cutoff-based findings require external validation.