Prostate cancer is the most common non-cutaneous cancer among men and is the second leading cause of death from cancer in men. Localized prostate cancer may be cured with surgery or radiation therapy, but the disease recurs in approximately 20% to 30% of patients. Patients whose disease progresses despite castrate levels of testosterone (<50 ng/dl), are referred to as having Castrate Resistant Prostate Cancer (CRPC).
Although the reason for the development of CRPC is not fully understood, it has been suggested that there is a small proportion of undifferentiated cancer cells present within the tumor that possess stem cell-like properties that is responsible for its recurrence.[1, 2] These cells are not dependent on androgen for survival and are resistant to chemotherapy.
Tocotrienol: Prostate Cancer Stem Cell Fighting Properties
Results published in the British Journal of Cancer (2008)  showed that among the various tocotrienol isomers, gamma-tocotrienol has the most potent anti-prostate cancer activity. Gamma-tocotrienol’s potent anti-cancer effects have been associated with its ability to suppress key inflammatory proteins including NF-кβ.
Results from a study conducted by scientists from Davos Life Science demonstrated for the first time that gamma-tocotrienols could kill the very small group of prostate cancer stem cells (PCSC) found in androgen-independent prostate cancer cell lines. The study which was published in the International Journal of Cancer (2010) showed that the spheroid formation ability of the prostate cancer cells, which is a key characteristic of stem cells, was significantly hampered by treatment with gamma-tocotrienol. Further, the study demonstrated that gamma-tocotrienol is able to kill PCSC that were unaffected by the anti-cancer drug docetaxel. Importantly, it also showed that gamma- tocotrienol could prevent the formation of cancer tumors from developing in 75% of mice implanted with prostate cancer cells as compared to 100% tumor formation in the control group. 
A multi-centre Phase I/II trial using gamma rich tocotrienols is being conducted in CRPC subjects in Malaysia and Australia.
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1. Collins AT & Maitland NJ. Prostate cancer stem cells. Eur J Cancer, 2006. 42(9): 1213-8.
2. Korkaya H & Wicha MS. Selective targeting of cancer stem cells: a new concept in cancer therapeutics. BioDrugs, 2007;21(5):299-310.