The relationship between KMO and cancer establishment was further analyzed using bioinformatics functional tools, including the Gene Ontology (GO), the Kyoto Encyclopedia of Genes and Genomes (KEGG), and the Protein–Protein Interaction (PPI) databases, to probe whether the expression of KMO is correlated to tumorigenesis in breast cancers and thereby whether it could serve as a biomarker related to cancer malignancy. The gene discussed is KMO; the disease is breast carcinoma.