Tumor-infiltrating tryptase⁺ mast cells predict unfavorable clinical outcome in solid tumors

The prognostic role of tumor-infiltrating tryptase⁺ mast cells in human solid tumors remains controversial. Herein, we conducted a meta-analysis including 28 published studies with 4224 patients identified from PubMed and EBSCO to assess the prognostic impact of tumor-infiltrating tryptase⁺ mast cells in human solid tumors. We found that tryptase⁺ mast cell infiltration significantly decreased overall survival (OS) and disease-free survival (DFS) in all types of solid tumors. In stratified analyses, tryptase⁺ mast cell infiltration was significantly associated with worse OS in non-small cell lung cancer, hepatocellular carcinoma and 5-year survival in colorectal cancer. And these cells were inversely associated with DFS in hepatocellular and colorectal cancer. In addition, high density of intratumoral tryptase⁺ mast cells significantly correlated with lymph node metastasis of solid tumor. In conclusion, Tryptase⁺ mast cell infiltration leads to an unfavorable clinical outcome in solid tumors, implicating that it is a valuable biomarker for prognostic prediction for human solid malignances and targeting it may have a potential for effective treatment.