Breast and other cancers need a good supply of blood to deliver the oxygen and nutrients that cancer cells need to grow, function, and multiply. To get that blood, cancer cells have ways of stimulating the growth of new blood vessels into the tumor. Avastin works by blocking this growth of new blood vessels, which starves the cancer of nutrients.
The growth of new blood vessels into a tumor is called angiogenesis (“angio” means blood vessel and “genesis” means beginning). Cancer cells can make a protein, called vascular endothelial growth factor (VEGF), to stimulate angiogenesis. Avastin blocks VEGF. By blocking VEGF, Avastin can interfere with the growth of new blood vessels into breast cancer tissue and starve the cancer. Doctors use the term anti-angiogenic to describe Avastin, because it works against the formation of blood vessels. Avastin can also change blood vessels already feeding the cancer in ways that make it harder for the cancer to survive and more vulnerable to chemotherapy. Avastin is an immune targeted therapy.