The Role of Salivary Microbiota in Pancreatic Cancer: From Screening to Tumor Progression and Treatment Response

Pancreatic cancer (PC) remains one of the malignancies with the most unfavorable prognosis and limited treatment options. The lack of biomarkers for early diagnosis and the asymptomatic nature of the disease contribute to delays in diagnosis and high mortality rates. In recent years, the role of the human microbiota in cancer biology has become increasingly significant, and the oral microbiota in particular has been found to be involved in the pathogenesis and prognosis of several neoplasms. This review summarizes the current evidence relating the salivary microbiota to PC in three key areas: screening and diagnostic potential, pathophysiology and tumor progression, as well as presenting prognostic implications and potential influence on therapy. With regard to early diagnosis, it has been reported that patients with PC have reduced levels of Neisseria elongata (N. elongata) and Streptococcus mitis (S. mitis) and elevated levels of Granulicatella adiacens. Several studies have shown that bacteria present in the saliva can migrate from the oral cavity to pancreatic tissue via hematogenous or enteric routes, where they may actively contribute to tumor development and progression. In particular, it has been shown that Porphyromonas gingivalis (P. gingivalis) and Veillonella atypica (V. atypica) translocate from the mouth to pancreatic tumors, promoting carcinogenesis by inducing a pro-inflammatory tumor microenvironment. Furthermore, some studies have identified certain species associated with prognosis and response to PC treatment. Despite the encouraging results, differences in study methodology, the lack of standardized methods and the scarcity of longitudinal data currently hinder clinical application. Large-scale, multi-omics prospective studies are needed to clarify causality and validate their clinical utility. Overall, the salivary microbiota represents a promising and non-invasive tool for improving early diagnosis, understanding prognosis and enhancing the management of PC.