Prostate cancer is a form of cancer that develops in the prostate, a gland in the male reproductive system. Most prostate cancers are slow growing; however, there are cases of aggressive prostate cancers. Men who ate a low-fat diet with fish oil supplements for four to six weeks before having their prostate removed had slower cancer-cell growth in their prostate tissue than men who ate a traditional, high-fat Western diet, according to a study by researchers at UCLA's Jonsson Comprehensive Cancer Center. The researchers also found a change in the composition of cell membranes in both healthy cells and cancer cells in the prostates of men on the low-fat, fish oil-supplement diet. The membranes had heightened levels of omega-3 fatty acids from fish oil and decreased levels of omega-6 fatty acids from corn oil, which may directly affect the biology of the cells, though further studies are needed, said Dr. William Aronson, the study's first author and a researcher with the Jonsson Cancer Center.
Prostate cancer is a form of cancer that develops in the prostate, a gland in the male reproductive system. Most prostate cancers are slow growing; however, there are cases of aggressive prostate cancers. Men who ate a low-fat diet with fish oil supplements for four to six weeks before having their prostate removed had slower cancer-cell growth in their prostate tissue than men who ate a traditional, high-fat Western diet, according to a study by researchers at UCLA's Jonsson Comprehensive Cancer Center. The researchers also found a change in the composition of cell membranes in both healthy cells and cancer cells in the prostates of men on the low-fat, fish oil-supplement diet. The membranes had heightened levels of omega-3 fatty acids from fish oil and decreased levels of omega-6 fatty acids from corn oil, which may directly affect the biology of the cells, though further studies are needed, said Dr. William Aronson, the study's first author and a researcher with the Jonsson Cancer Center.
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The prostate is a compound tubuloalveolar exocrine gland of the male reproductive system in most mammals.
While a number of dietary factors have been linked to prostate cancer the evidence is still tentative. Evidence supports little role for dietary fruits and vegetables in prostate cancer occurrence. Red meat and processed meat also appear to have little effect. Lower blood levels of vitamin D may increase the risk of developing prostate cancer.
The new short-term diet study also found that blood obtained from patients after the low-fat, fish oil diet slowed the growth of prostate cancer cells in a test tube, while blood from men on the Western diet did not slow cancer growth.
"The finding that the low-fat, fish oil diet reduced the number of rapidly dividing cells in the prostate cancer tissue is important because the rate at which the cells are dividing can be predictive of future cancer progression," Aronson said. "The lower the rate of proliferation, the lesser the chances that the cancer will spread outside the prostate, where it is much harder to treat."
The findings are published in the Cancer Prevention Research, a peer-reviewed journal of the American Association for Cancer Research.
Aronson said using human blood and tissue in this study proved that the changes prompted by what the men were eating were clearly evident in their prostate tissue — that the treatment was indeed reaching the targeted organ because of the changes in the prostate cell membranes' fatty acid composition.
Aronson measured proliferation — the rate of prostate cancer cell division — by staining tissue obtained from the radical prostatectomy specimens with an antibody against Ki-67, a protein involved in the cell-cycle progression and growth.
"The percentage of prostate cancer cells that stained for Ki-67 was determined by the pathologist, and this gave us an objective measurement of the percentage of cells that were actively dividing and therefore more aggressive," Aronson said. "Previous studies found that patients with higher levels of Ki-67 in their prostate cancer tissue were more likely to have their prostate cancer progress to advanced stages and were more likely to die from their prostate cancer. Thus, we are extremely encouraged by our findings that a low-fat diet with fish oil lowered Ki-67 levels and may have the potential to slow the progression of prostate cancer."
Diet studies often are difficult to evaluate because getting patients to comply with dietary changes can be challenging. However, the food eaten by men in both arms of this study was precisely controlled, Aronson said. The meals were prepared by chefs at the UCLA Clinical Translational Research Center and delivered in bulk to study participants several times a week. Participants also met with a dietician, kept food diaries and were required to return uneaten food.
With the study's Western diet, 40 percent of the calories came from fat, which is generally equivalent to what many Americans consume today. The fat sources also were typical of the American diet and included high levels of omega-6 fatty acids from corn oil and low levels of fish oil that provides omega-3 fatty acids.
"Preclinical studies suggest that lowering dietary omega-6 fatty acids from corn oil and increasing omega-3 fatty acids from fish oil decreases the risk of prostate cancer development and progression," the study states. "We found this diet intervention resulted in a decrease in omega-6 vs. omega-3 fatty acid ratios in benign and malignant prostate tissue and a decrease in malignant cell proliferation."
For further information: http://www.universityofcalifornia.edu/news/article/26547
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