Neovascularization: an attractive but tricky target in thyroid cancer

Neovascularization in carcinogenesis and tumor progression is well-established. Molecular mediators implicated in different modes of vascular remodeling and expansion (e.g. sprouting angiogenesis (SA), vasculogenesis, vascular mimicry) are evaluated as prognostic biomarkers and therapeutic targets in different malignant tumors. Significant progress has been made in the understanding of the complex interplay between thyroid cancer (TC) cells and the tumor microenvironment, thus unraveling the role of angiogenic mediators. Areas covered: This review summarizes current research on neovascularization and TC. Current knowledge on vascular remodeling, in the context of carcinogenesis, is presented. Preclinical and clinical data from TC studies are also discussed. Expert opinion: There is a remarkable effort to pharmacologically target several key molecules of vessel-forming cascades. Despite encouraging preclinical results, clinical outcomes in TC are not optimal, possibly reflecting knowledge gaps in the pathophysiology of neovascularization in thyroid tissue. Increasing amounts of data support the possibility that redundancy of pathways that regulate vascular network remodeling allows tumors to adapt in different conditions. Hypothesizing that alternative forms of neovascularization upregulate when SA is pharmacologically blocked, targeting two or more different pathways of neovascularization could be a promising future strategy. Further research is required to explore molecular mechanisms of neovascularization in TC.