A gene set enrichment analysis for the cancer hallmarks

The "hallmarks of cancer" concept provides a valuable framework for understanding fundamental organizing principles common to various cancers. However, without a consensus gene set for cancer hallmarks, data comparison and integration result in diverse biological interpretations across studies. Therefore, we aimed to form a consensus cancer hallmark gene set by merging data from available mapping resources and establishing a framework for mining these gene sets. By consolidating data from seven projects, 6,763 genes associated with ten cancer hallmarks were identified. A cancer hallmarks enrichment analysis was performed for prognostic genes associated with overall survival across twelve types of solid tumors. "Tissue invasion and metastasis" was most prominent in cancers of the stomach (P = 2.2×10^-11), pancreas (P = 4.2×10^-9), bladder (P = 3.3×10^-8), and ovaries (P = 0.0007), aligning with their heightened potential to spread. "Sustained angiogenesis" was most prominent in squamous cell carcinomas of the lung (P = 2.5×10^-7), while "genome instability" showed strong enrichment in lung adenocarcinomas (P = 1.5×10^-8) and cancers of the liver (P = 5.5×10^-10), pancreas (P = 2.1×10^-5), and kidney (P = 0.018). Pancreatic cancers displayed the highest enrichment of hallmarks, emphasizing the disease's complexity, while in melanomas, and cancers of the liver, prostate, and kidney, a single hallmark was enriched among the prognostic markers of survival. Additionally, an online tool (www.cancerhallmarks.com) that allows the identification of cancer-associated hallmarks from new gene sets was established. In summary, our aim of establishing a consensus list of cancer hallmark genes was achieved. Furthermore, the analysis of survival-associated genes revealed a unique pattern of hallmark enrichment with potential pharmacological implications in different tumor types.