Recent data has suggested that both proteins are among the most up-regulated genes in a number of acute and chronic inflammatory diseases, including cystic fibrosis, chronic inflammatory bowel disorder, Kawasaki disease and systemic lupus erythematosus, allergic dermatitis, and infection.21–24 Abnormal expression of S100A8 and S100A9 has been reported in various cancers, such as breast, lung, gastric, and colorectal cancer.25–27 However, the clinical importance of S100A8 and S100A9 expression in PQ poisoning has not previously been investigated. Here, S100A9 is linked to cancer.