GDF15 and lung cancer: GDF-15 overexpression has been observed in several types of tumor disease, such as glioblastoma [14, 15], testicular cancer [16], ovarian cancer [17], oral squamous cell carcinoma [18], uveal melanoma [19], hepatocellular carcinoma [20], lung cancer [21], prostate, breast, colon, and gastric cancer [10, 22], including pancreatic cancer [23–28].