Angiogenesis Factors. Angiogenesis is the growth of new blood vessels. High levels of angiogenesis factors indicate that the tumor is developing its own supply of blood vessels, which enable the tumor to send colonies of cancer cells into the blood stream and spread to other parts of the body. Specific angiogenesis factors, such as vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF), may turn out to be important markers for determining treatment and prognosis. The monoclonal antibody bevacizumab (Avastin) targets VEGF. The drug is showing promise in clinical trials for prolonging progression-free survival in women with metastatic breast cancer.
Others. Many other markers are being investigated, including p53, cathepsin-D, protein c-erbB-2, bcl-2, Ki-67, telomerase, thymidylate synthase, CA 15-3, and carcinogenic embryonic antigen (CEA). The American Society of Clinical Oncology (ASCO) cautions, however, that the value of many of these factors has not yet been confirmed.
Other Factors for Predicting Outlook
Tumor Size and Shape. Large tumors pose a higher risk than small tumors. Undifferentiated tumors, which have indistinct margins, are more dangerous than those with well-defined margins.
Rate of Cell Division. The more rapidly a tumor grows, the more dangerous it is. Several tests measure aspects of cancer cell division and may eventually prove to predict the disease. For example, the mitotic index (MI) is a measurement of the rate at which cells divide. The higher the MI, the more aggressive the cancer. Another test measures cells at a certain phase of their division.
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