Western diet may accelerate prostate metastasis to lungs
MedWire News: The cholesterol and fat content of a Western-style diet may increase the risk for prostate cancer metastasis to the lungs, show US study findings published in the American Journal of Pathology.
The study, undertaken in mice, also revealed that those fed a Western diet as opposed to a low-fat minimal cholesterol diet had increased plasma cholesterol levels and fat deposits, which accelerated prostate tumor progression and exacerbated its aggressiveness.
"The mechanisms by which dietary fat or cholesterol could be promoting metastasis formation need to be further evaluated," say Philippe Frank and colleagues from the Thomas Jefferson University in Philadelphia, Pennsylvania.
"Nevertheless, given the overall health benefits of controlling plasma cholesterol levels and body weight, in addition to the possible benefits offered to the prostate, it appears that managing cholesterol metabolism would be a prudent plan for all men," they add.
The study involved feeding two groups of mice either a Western-style diet containing 21.2% fat and 0.2% cholesterol, or a normal chow diet including 4.5% fat and negligible amounts (0.002%) of cholesterol.
At 28 weeks, 33% (6 of 18) of mice fed the Western diet showed a "grossly evident spherical prostate tumor," report Frank et al, compared with 17% (3 of 17) of the chow-fed mice.
After accounting for the total tumor weight per mouse, animals fed the Western diet had also developed larger tumors than those fed a chow diet, with tumors weighing an average 6.00 g versus 2.42 g.
These results suggest "an important role for dietary fat and cholesterol in prostate tumor formation," write the researchers.
Mice fed a Western diet also displayed a worsening of histological grade compared with mice fed a chow diet, as evidenced by markedly distended glands and foci of tumor invasion. Considering the link between histological grade and metastasis, Frank and team sought an association between diet and tumor progression of this nature.
They found significantly higher levels of pulmonary metastasis in mice fed the higher cholesterol and fat diet (67%) compared with mice fed a normal diet (43%).
Interestingly, remarks the team, mice fed a Western diet showed a significant reduction in plasma cholesterol levels at 28 weeks of age, despite the fact that they had elevated levels compared with chow-fed mice at both 22, and 28 weeks of age.
"This likely reflects the fact that their tumors depend on cholesterol to grow," said Frank.
He also offered a physiological explanation for the link between cholesterol and tumorigenesis: "Cells need cholesterol to produce androgen hormones, and androgen hormones promote prostate cancer growth."
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By Sarah Guy