Vascular normalization window: A positive prognostic foresight for head and neck cancer

Abstract

Tumor angiogenesis is a hallmark of advanced cancers which is critical for the continued growth and progression of solid tumors owing to the metastatic spread of tumor cells. This knowledge has led to the concept of targeting the tumor vasculature as a therapeutic modality. Several retrospective studies support the positive prognosis for the implications of angiogenic markers for head and neck squamous cell carcinoma (HNSCC), currently making them an attractive target oriented treatment. Radiotherapy (RT) being the conventional treatment for HNSCC, makes it imperative in this present era to recognize the communication between antiangiogenic therapy and RT, thus developing a combination therapy to achieve progress in the outcome of clinical practice. The combination of antiangiogenic agents and ionizing radiation involve many interactions between the cells, the stroma of the tumor and tissue vasculature. Increased angiogenesis is responsible for the proliferation of tumor cells and its metastasis which ultimately leads to tumor hypoxia. Any agent targeting the tumor vasculature can modulate the tumor microenvironment thus normalizing it and enhancing the therapeutic response of hypoxic cells of head and neck cancers. This review provides insight into the mechanisms by which the antiangiogenic therapy combined with RT improves the tumor response to radiation, thereby suggesting a promising prognostic treatment modality of HNSCC in the time ahead.