Metastatic renal cell carcinoma
Approximately 20–30% of renal cell carcinoma (RCC) patients have detectable metastatic disease and the disease has already spread to other organs at the time of diagnosis. In addition, many of those patients with non-metastatic RCC treated by surgery suffer a metastatic relapse as described above. Recurrent and advanced-stage RCC are extremely difficult to treat and conventional chemotherapy is almost ineffective. As a treatment for patients with metastatic RCC, cytokines such as interferon-alpha (IFNα) and interleukin-2 (IL-2) are currently given. However, their use is limited by modest response rates and severe side effects. Since 2003, the direction of kidney cancer clinical research has shifted from almost total reliance on immunotherapies (IL-2 and IFN) to an emphasis on investigational drugs that target various cellular mechanisms regulating cancer cell growth and proliferation. Specifically, the new therapies are targeted to work by at least three, and perhaps more, mechanisms of action (Kidney Cancer Journal, Vol. 3, No. 2, Summer 2005, www.wilex.com):
- By inhibiting the growth of new blood vessels, which in turn nourish the growth of new tumor cells (angiogenesis)
- By inhibiting specialized cells called pericytes, that stabilize new blood vessels
- By correcting the normal body mechanism that allows living cells, including cancer cells, to die naturally. This process is known as apoptosis. Most body cells divide about seven times before they undergo genetically programmed cell death, but cancer cells continue dividing indefinitely.
It is widely believed, but not yet proven by researchers, that combining drugs in a multi-targeted approach will probably lead to the most effective results. In another recent development, researchers are beginning to take this approach by combining the new targeted therapies with the older, standard immunotherapies.
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