Periodontal Status and Gingival Crevicular Fluid Fusobacterium nucleatum and Cathepsin K Assessment in Patients with Gastric Cancer

<b>Background/Objectives</b>: Periodontal disease, the most widespread chronic inflammatory non-communicable disease, is caused by the host-mediated inflammatory and immune responses to the bacterial biofilm. <i>Fusobacterium nucleatum</i> contributes to its progression and is associated with gastrointestinal cancers, including gastric cancer (GC), by promoting inflammation and immune evasion. Additionally, cathepsin K (CTSK) enhances tumor invasiveness and metastasis, playing a crucial role in GC progression. <b>Aim</b>: The present study was carried out to evaluate the possible association between the amount of <i>F. nucleatum</i> from gingival crevicular fluid and the periodontal status with the characteristics of GC. <b>Methods</b>: This cross-sectional study included 48 GC patients with periodontal changes, presenting to the Surgery Department in Craiova, Romania, from March 2023 to February 2024. Clinical assessments, where the number of teeth present, probing depth (PD), and bleeding on probing (BOP) were recorded, gingival crevicular fluid sampling, qPCR for <i>Fusobacterium nucleatum</i>, and ELISA for cathepsin K were performed. Histological analysis evaluated tumor characteristics, where tumor dimension (TD) and differentiation grade (DG) were recorded, and statistical analysis was conducted using R software. <b>Results</b>: Smokers presented higher PD and <i>F. nucleatum</i> levels than non-smokers. Gender had no impact on PD, BOP, CTSK, <i>F. nucleatum</i>, or TD. PD correlated with <i>F. nucleatum</i>, TD, and CTSK. <i>F. nucleatum</i> strongly correlated with CTSK and TD, and CTSK was strongly correlated with TD. <b>Conclusions</b>: These results suggest an association between <i>F. nucleatum</i>, periodontal parameters, and characteristics of GC but future studies are needed.