However, there is no pan-cancer research to comprehensively analyze COL1A1. Therefore, we expanded the research scope to pan-cancer and analyzed its gene expression level, mutation, DNA methylation, tumor prognosis, tumor immune microenvironment, and the association with predictive markers of immunotherapy, the pathway, and drug sensitivity in 33 kinds of tumors. The gene discussed is COL1A1; the disease is neoplasm.