The in vivo results indicated that P. intermedia accelerated tumor growth, promoted muscle and perineural invasion of OSCC, elevated serum levels of proinflammatory cytokines, upregulated the expression of proinflammatory cytokines in OSCC tissues, augmented the infiltration of M2 macrophages and Tregs, activated the expression of key molecules in the IL-17A signaling pathway, and inhibited the GABA signaling pathway and an array of tumor suppressor genes in tumor tissues. This evidence concerns the gene IL17A and neoplasm.