Additional features of solid TumorHaematological malignancies occur in cells which are already anchorage-independent and circulating. However, additional features are required for a solid tumor to grow and metastasis. The acquisition of additional mutations means that the secondary tumor cells may replicate faster than the primary, or be unable to differentiate as fully.
The blood supply to the enlarging mass of cells is initially rate-limiting, as evidenced by the ischaemic centers to solid Tumours. Some Tumours may acquire mutations to enhance the secretion of factors to stimulate neovascularisation (angiogenesis), but in many instances physiology suffices since hypoxia is a potent stimulus of the angiogenic factor VEGEF (vascular endothelial cell growth factor).