[Vascularization and perfusion of tumors as target in cancer therapy]

Many tumours depend on the formation of an own vascular system to support progressive tumour growth. This is accomplished through induction of vessel growth from pre-existing vessels, a process called neo-angiogenesis. Therefore, inhibiting neo-angiogenesis and modulating tumour perfusion constitute attractive possibilities for tumour therapy, combined, of course, with treatment aimed at the tumour cells themselves. By now many angiogenesis inhibitors have been developed, but their use is mostly still experimental. They inhibit endothelial proliferation and migration (fumagillin derivates, angiostatin, suramin) or prevent proteolytic degeneration of the extracellular matrix by products of the tumour (metalloproteinase inhibitors). Improving tumour oxygenation and perfusion by carbogen inhalation and nicotinamide or vasoactive agents (flunarizine, verapamil, nicotinamide) enhances the effects of radiotherapy and improves delivery of chemotherapeutic agents to the tumour. Research is currently in progress into the efficacy of accelerated radiotherapy in combination with carbogen inhalation and administration of nicotinamide in tumours of the head and neck, bladder, bronchi and brain.