However, pharmacokinetic studies have indicated that the half-life of the IFN-α protein is 3 h in the blood circulation and only 0.01% of subcutaneously injected IFN-α can reach the target sites (Salmon et al, 1996; Suzuki et al, 2003), indicating that IFN-α protein delivery might be insufficient and/or at an unsustainable level in the tumour site. This evidence concerns the gene IFNA2 and neoplasm.