As well as the aforementioned role of PLTs in tumor metastasis, the possible roles of PLTs in tumor growth and angiogenesis may explain this unfavorable prognostic effect; for example, PLTs are able to secrete a number of proangiogenic cytokines, including vascular endothelial growth factor (30) and thymidine phosphorylase (31). This evidence concerns the gene TYMP and neoplasm.