Several systematic reviews have explored the use of pyruvate kinase in the diagnosis of cancers: Hathurusinghe et al. [23] concluded that PMK2 was elevated in a range of gastrointestinal malignancies; Uppara et al. [24] demonstrated that PKM2 had relatively good sensitivity (79%) and specificity (80%) for screening for colorectal cancer, and Wang et al. [25] determined that PKM2 had moderate performance in the diagnosis of biliary tract carcinoma. The gene discussed is PKM; the disease is cancer.