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Prostate cancer is the most diagnosed cancer and second leading cause of cancer-related death in American men. Prostate cancer is commonly treated by hormone therapy which depletes androgens, thereby slowing abnormal growth. Development into advanced stage prostate cancer, hormone refractory prostate cancer (HRPC), is typically unresponsive to androgen treatment and at present has no cure. Epidemiological studies have indicated that populations that ingest diets rich in omega-3 fatty acids have lower incidences of cancer. Omega-3 fatty acids have been found to decrease the growth of several cancers both in vitro and in vivo and have lowered the effective dosage of chemotherapeutic drugs when used in combination. Taxotere® has been used successfully as a treatment for several different cancers, and two large-scale phase III clinical trials have indicated the benefit of its use in combination with other regimens in the treatment of prostate cancer. Previous studies in this lab have found that docosahexaenoic acid (DHA) - a component of fish oil - is the tumor reducing omega-3 fatty acid for both androgen dependent and androgen independent prostate cancer cell lines. Western diets often consist of a ratio of 15-16.7:1 of omega-6 to omega-3 fatty acids. Several preliminary feeding studies were performed to determine the optimum dietary ratio of the known tumor promoting omega-6 fatty acid linoleic acid (LA) to DHA with tumor bearing mice in vivo. These studies indicate that with increasing amounts of DHA, tumor growth rate is slowed. However, the mice with higher DHA intake exhibited lower body weight that may be a factor to consider for use in the clinical setting. An additional study has evaluated the effect of omega-3 fatty acids in combination with Taxotere® on HRPC in an athymic nude mouse model. This study indicates that diets rich in omega-3 fatty acids, particularly DHA, exhibit a trend toward smaller tumor growth when compared to omega-6 diet controls. The diet enriched in DHA reduced the growth rates of PC-3 tumors when compared to other diets administered. All high fat diets regardless of fat composition responded to Taxotere® better than the low fat control diet. Further studies are underway to elucidate the advantages of high fat diets paired with Taxotere® and to discover the mechanism of omega-3 fatty acid inhibition of HRPC.

[Proc Amer Assoc Cancer Res, Volume 47, 2006]