Low-Fat Diet and Fish Oil Supplementation Reduces Cell-Cycle Progression in Prostate Cancer
In a post hoc analysis reported in the journal Cancer Prevention Research, Galet et al analyzed the effects of diet on men with prostate cancer. They found that men who were on a low-fat diet and fish oil supplementation had lower cell-cycle progression scores, which are associated with less aggressive cancer. This study is a follow-up to a 2011 phase II prospective randomized trial conducted by the same team of researchers.
Study Details
The 2011 study compared men with prostate cancer who consumed a typical high-fat Western diet with those who were on a low-fat diet and took fish oil supplements. The fat content for those on the Western diet was 40%. In contrast, the fat content for those on the low-fat diet was 15%.
The fat sources included high levels of omega-6 fatty acids from corn oil (particularly linoleic acid) and low levels of fish oil, which provides omega-3 fatty acids. Men on the low-fat fish oil diet took five capsules (5 g/capsule) of fish oil per day, three with breakfast and two with dinner. The investigators concluded from the earlier study that a low-fat fish oil diet for 4 to 6 weeks did not influence serum IGF-1 levels but did lower omega-6 to omega-3 fatty acid ratios.
The current study is based on serum and prostate tissue samples from the 2011 study. The Western diet group included 21 patients, and the low-fat fish oil diet group contained 27 patients. Most of the patients in both groups were characterized as being overweight or obese. Patients maintained their respective diet for a period of 28 to 30 days.
Analysis of fatty acid levels was achieved via gas chromatography. The researchers examined proinflammatory eicosanoids such as leukotriene B4 and 15-S-hydroxyeicosatetraenoic acid. (Leukotriene B4 is formed through the 5-lipoxygenase pathway, and 15-S-hydroxyeicosatetraenoic acid, the major hydroxy derivative of arachidonic acid, is the end product of 15-lipoxygenase.) It should be noted that it has been previously validated that expression of the leukotriene B4 receptor BLT1 is associated with cell proliferation.
Cell cycle progression scores were measured from 16 patients from the Western diet group and 20 patients from the low-fat fish oil diet group. In some cases, the cell cycle progression score has been shown to be a predictor of prostate cancer recurrence.
Clinical Significance
A significant finding from the current study was that in men on the low-fat fish oil diet, there was a decrease in the omega-6 to omega-3 fatty acid ratio. In addition, 15-S-hydroxyeicosatetraenoic acid levels were reduced in this group of patients as well.
As for the cell cycle progression scores, they were found to be lower in patients on the low-fat fish oil diet than in those on the Western diet. Indeed, analyses showed a significant positive correlation between changes in leukotriene B4 levels with cell cycle progression scores.
The investigators concluded, “With the help of reliable cell cycle progression scores and other markers, we may be able to predict which patients’ prostate cancer will recur and treat accordingly. Our study suggests that by altering the diet, we may favorably affect the biology of prostate cancer.”
William J. Aronson, MD, of the UCLA Jonsson Comprehensive Cancer Center, is corresponding author for the article in Cancer Prevention Research.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
