IGFBP3 and lung cancer: The circulating IGFBP-3 concentrations of blood samples collected years before detectable lung cancer were of no difference with that of the control participants (people who involved in the prospective studies without lung cancer until the endpoint of the studies); whereas, when it came to the case-control studies, the circulating IGFBP-3 concentrations of blood samples from the definitely diagnosed lung cancer patients were significantly lower than that of the control participants.