CD274 and cancer: Porphyromonas and Prevotella significantly increased in patients with OSCC, while in the PD-L1 positive group, the abundance of Clostridium subcluster XIVa in the intestinal flora was significantly higher than that in the PD-L1 negative group. Studies also show that there is an ecological imbalance in the oral and intestinal microbiota of OSCC patients. The results suggest that probiotics and synthetic bacteria targeting these disease-specific microbiota may offer possibilities for new cancer treatment methods.