FIGURE 2.

Schematic representation of the rationale for combining radiotherapy and VDAs.

The result of VDA treatment is selective destruction of tumor vessels which causes extensive central tumor necrosis leaving only a thin layer of viable cells at the tumor periphery. These cells are believed to obtain nutrients and oxygen from vessels of the surrounding normal tissue and their repopulation may be the cause of treatment failure when VDAs are used in monotherapy. Combined treatment of VDA with radiotherapy may be more successful as radiation can destroy the viable tumor rim of well oxygenated and thus radiosensitive peripheral tumor cells remaining after the use of VDA.