Table 1.

Composition of the TM in tumors and its relationship to clinical features and tumor immunity.

Tumor Type	Common TM	Relationship to clinical features	Relationship with tumor immunity	References
Prostate Cancer	Staphylococcus, Propionibacterium, Acinetobacter and Pseudomonas	Pseudomonas infection may impede metastasis	CP1 increases T cell toxicity and immune death of tumor cells	(40,46)
Pancreatic Cancer	Enterobacteriaceae and Pseudomonadaceae	TM mediates resistance of tumor cells to gemcitabine. Patients with high TM alpha-diversity had longer overall survival.	The TM mediates anti-tumor immunity through activation of CD8+T cells.	(32, 38, 50)
Breast Cancer	Pseudomonadaceae, Enterobacteriaceae, Proteus	Lymphovascular invasion was positively correlated with Lactobacillus and negatively with Alkanindiges. In a mouse model, Staphylococcus and Lactobacillus promote lung metastasis of BC.	Methylibium, Pelomonas, Propionibacterium were identified as nodes in the microbiome-immune gene and microbiome-cytokine networks	(54, 55)
Lung Cancer	Acidovorax, Veillonella parvula,	Acidovorax are abundant in lung cancer patients who smoke. Veillonella parvula is associated with poor prognosis	Veillonella parvula led to the recruitment of Th17 cells, increased levels of IL-17 and PD-1+ T cells. Commensal bacteria induce the proliferation and activation of γδ T cells thereby promoting the proliferation of LC cells.	(18, 63, 64)
Gastric Cancer	Peptostreptococcus, Streptococcus and Fusobacterium	Changes in the abundance of oral microbiota in the stomach may be associated with the development or progression of GC.	HP infection enhanced PD-L1 expression in human gastric epithelial cells and led to non-specific suppression of circulating T cells	(66, 70)
Ovarian Cancer	Proteobacteria, Firmicutes, Aquificae and Planctomycetes	LPS stimulation of OC cells enhances invasion and induces production of EMT-associated cytokines	–	(72–74)
Melanoma	Propionibacterium, Staphylococcus and Corynebacterium	Compared with stage T1/T2 melanoma, a significant increase in Corynebacterium was detected in T3/T4 melanoma	More IL-17-positive cells were detected in Corynebacterium-positive patients	(83)
Colorectal cancer	Fusobacterium and Providencia	F. nucleatum can promote CRC metastasis through multiple pathways	F. nucleatum-positive CRLM showed a significantly lower density of CD8+ T cells and a higher density of MDSCs compared to F. nucleatum-negative CRLM	(90, 96)