Cancer cells are masters of deceit and veritable Houdinis that can readily alter themselves to evade immunologic recognition and attack. Perhaps these therapies will yield the universal objective of cancer researchers, health care providers and, of course, patients. A more achievable aim, though, may be developing therapies that can change the nature of cancer from a progressive and lethal disease to one that can be controlled throughout a long life. That result would be less than ideal, but it could make a world of difference for many afflicted with tumors not readily treatable today. 5 Anti-angiogenesis factors To grow beyond the size of a small pea, all solid tumors require their own blood supply to deliver nutrients.
Tumors thus have to force the construction of special blood vessels.
To accomplish this, they secrete substances that stimulate blood vessel growth in neighboring tissue, inducing the nearest blood vessels to grow new branches in their direction, a process known as angiogenesis. Some of these cells are not angiogenic but are nonetheless sustained by capillaries recruited by neighboring cells. Now the tumor can expand in a matter of months, the mass may reach one cubic centimeter in size and contain around one billion tumor cells. Dozens of substances are currently being tested that block angiogenesis, although some chemicals identified as anti-angiogenic, like interferon, have proved too weak to produce significant effects in highly malignant tumors. Antiangiogenic therapy, in contrast to many other therapeutic approaches, does not aim to destroy tumors.