Cancer Stem Cells
Cancer, specifically solid tumors, may be viewed as a two-compartment, three-dimensional model. On the surface of the tumor are cancer cells that lie adjacent to the blood supply; these cells are well-nourished and have little need to develop mechanisms to stay alive. The core of the tumor commonly lacks sufficient blood supply; these cells in the core are poorly nourished and must develop mechanisms to survive. These core cells tend to feed on sugar through a method known as glycolysis. Glycolysis allows the cancer cell to develop energy without the presence of oxygen. These cells tend to be extremely hardy and resistant to chemotherapy and radiation. In addition, because of their poor blood supply, they are usually not exposed to high levels of chemotherapy. In the core, as well as non-core regions that are poorly vascularized, is where we often find quiescent, or resting, cancer cells, as well as the cancer stem cells. It is the cancer stem cells that have the ability to self-renew. Conventional cancer treatment for advanced stage cancers consist of maximum tolerated dose chemotherapy, as well as radiation for local control. Unfortunately, five year survival for the advanced stage solid tumors has minimally improved over the last 50 years (Morgan G, Ward R, Barton M, Clinical Oncology, 2004), despite the development of targeted drugs and targeted agents. Recent studies have elucidated the mechanisms for the inability to improve survival with advanced-stage solid tumors.
Chemotherapy kills the rapidly dividing cells on the surface of the tumor, while leaving the cells in the inner core unscathed. With time, those inner-core cells, as well as the cancer stem cells will re-proliferate a new tumor that has produced daughter cells that are now extremely hardy and chemo resistant. Further studies have revealed that repeated chemotherapy and radiation treatments, given in the maximum tolerated dose fashion, actually induce daughter cells to acquire stem like properties. The end result of conventional therapy is to make a more aggressive cancer by increasing the pool of cancer stem cells, as well as increasing the pool of chemotherapy resistant cells. The patient initially improves with treatment because significant tumor burden is decreased; unfortunately, the tumor that has been killed consists only of the daughter cells. In a short time, the more resistant and aggressive cancer, which now contains more cancer stem cells, will rapidly progress and metastasize.
So, we need to consider a new paradigm; if we are to have success in treating advanced stage solid tumors, we must not only treat the daughter cells that are adjacent to adequate blood supply but we must also treat the cancer stem cells and the chemo-resistant cells. To learn if ICT's cancer treatment services are appropriate for you or to arrange an appointment, please call (561) 886-0976.