GDF15 and metastatic neoplasm: It has been observed that GDF15 expression levels are markedly enhanced in malignant tissues, established cancer cells and plasma during the transition of numerous localized cancers to invasive and metastatic disease stages as compared with non‐malignant tissues, normal cells, and basal GDF15 concentration in serum 12, 13, 14, 15, 16, 17, 18, 19, 20, 26, 27, 28, 29, 38, 39, 40, 41.