Background Secretory phosphoprotein 1 (SPP1) is a glyco-phosphoprotein that is widely expressed in a variety of cancer cells. Current studies have identified that SPP1 is differentially expressed in a variety of cancer cell species. However, there are few studies on the level of SPP1 expression in different types of cancer and its clinical significance. Methods In this study, we analyzed SPP1 levels and its significance in 33 different cancer types by using The Cancer Genome Atlas (TCGA)

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... e. The study analyzed the correlation between SPP1 expression and tumor immunity. Results The results showed that SPP1 transcript levels were aberrantly expressed in most tumors. Univariate Cox analysis showed that SPP1 was strongly associated with Overall survival in multiple tumor types. We also found that SPP1 was significantly correlated with tumor immune microenvironment, tumor immune cells, and tumor infiltrating lymphocyte markers. The correlation of SPP1 with Tumor mutational load (TMB) and Microsatellite instability (MSI) also predicts its role in assessing the efficacy of immunotherapy. Gene set enrichment analysis of 33 cancer types provided further evidence for the relationship between SPP1 levels and cancer progression and immune cell infiltration. Conclusion our study concludes that SPP1 plays an important role in tumorigenesis and tumor immunity and can be used as a marker for the assessment of clinical indicators in multiple cancer types.