Qin et al. [25] screened three VOCs (3-hydroxy-2-butanone, styrene, decane) as potential biomarkers for hepatocellular carcinoma and showed that 3-hydroxy-2-butanone had the best diagnostic value, without correlation with the alpha-fetoprotein (AFP) levels [25]. The gene discussed is AFP; the disease is hepatocellular carcinoma.