Supplementary Material for: 2,3-Pyridinedicarboxylate is associated with shorter recurrence-free survival in patients with hypopharyngeal squamous cell carcinoma

Introduction: Metabolites are associated with the biology of cancer; however, no metabolites related to prognosis have been identified in head and neck cancer. This study aimed to identify metabolites associated with prognosis in patients with hypopharyngeal squamous cell carcinoma (HPSCC).
Methods: Fifty-two patients who underwent surgery for HPSCC were included and randomly divided into test and validation cohorts of 26 patients each for further metabolome analysis using capillary electrophoresis/mass spectrometry on tumor and non-tumor tissues of the hypopharynx. Twenty-two patients who received adjuvant therapy after surgery were included. The receiver operating characteristic (ROC) and univariate and multivariate analyses were used to explore the relationship between recurrence-free survival (RFS), clinicopathological factors, and differentiated metabolites.
Results: ROC analysis revealed six metabolites significantly associated with RFS in both cohorts, and multivariate analysis indicated that 2,3-pyridinedicarboxylate was a significantly independent poorer prognostic factor in the cohorts including patients with HPSCC without any adjuvant therapies (P = 0.017).
Conclusion: 2,3-Pyridinedicarboxylate, involved in NAD+ metabolism and genomic stability, suggests the possibility of developing molecular-targeted drugs for the production of metabolites related to prognosis. This study identifies novel prognostic metabolites and their associated metabolic pathways in HPSCC, highlighting potential therapeutic targets for treatment.