Figure 6a:

Graphs show individual vascular leakiness (K^PS) values at tumor periphery estimated at MR imaging before and 24 hours after a single dose of (a) bevacizumab or (b) saline. Note that every angiogenically inhibited tumor decreased in estimated microvascular leakiness, while leakiness in three of four control saline-treated tumors and the mean leakiness value for all four saline-treated tumors increased over the same 24-hour period (Table). Apparently the natural trend for control tumors—at least in this human breast cancer model—is for increasing microvascular leakiness with increasing tumor age and growth. In theory, this could be a reflection of increasing VEGF production by the growing mass of tumor cells.