Consumption of Western-style diets rich in fat and cholesterol accelerate both the onset and progression of prostate cancer, finds a study in a mouse model of the disease. The US study, published in The American Journal of Pathology, shows that mice eating Western diets develop larger tumours that grow faster and metastasize more easily to the lungs when compared with animals eating control diets that are low in fat and cholesterol.

Epidemiological studies have provided evidence suggesting an important role for diet and obesity in the development of cancer, with lipids in particular identified as regulators of tumour development and progression. Additional evidence comes from the marked geographic differences in the incidence of prostate cancer, ranging from 2.3 per 100,000 men in China to 101 and 137 per 100,000 men in white and black Americans. Furthermore, the incidence of prostate cancer in Chinese and Japanese men increases substantially following migration to the US. “From these observations stems the hypothesis that environmental factors, most likely present in the diet, may act as late stage promoters responsible for the transformation of the prostate tumor from a latent form into a more aggressive and clinically apparent form,” write the authors, led by Philippe G Franks from the Department of Stem Cell Biology and Regenerative Medicine at Thomas Jefferson University (Philadelphia, Pennsylvania).

In the present study Franks and colleagues examined the hypothesis that increased dietary fat and cholesterol (and consequently increased plasma cholesterol levels) plays an important role in prostate cancer onset and progression.  For the purposes of the study the team used the transgenic adenocarcinoma of the mouse prostate (TRAMP) model, which is believed to closely parallel the pathogenesis of human prostate cancer.

In the study 8 week old TRAMP males were distributed to receive either a low-fat chow diet (containing 4.5% fat and 0.002% cholesterol, n=18) or a Western diet (containing 21.2% fat and 0.2 % cholesterol, n=17).   Both carbohydrate and calorific content of the two diets were similar.

When the mice were sacrificed at 18 weeks, 33% (6 of 18) TRAMP mice fed the Western diet showed gross evidence of prostate tumours compared to 17% (3 of 17) mice fed the control chow diet. When total tumour weight per mouse was taken into account, mice fed Western diets developed larger tumours with an average of 6.00 +- 2.09 g as compared to only 2.42 +- for mice fed chow diets. Furthermore, the investigators showed that Western diets increased the extent and histological grade of prostate tumours, a finding confirmed by the presence of increased levels of protein markers of advanced tumours in prostates obtained from animals fed western diets. In addition mice fed Western diets appeared to experience a greater incidence of cancer metastasis to the lungs and showed an increased angiogenic response. The investigators also found that TRAMP mice fed the high fat/high cholesterol diets had less cholesterol in their blood in comparison to control mice...

“This likely reflects the fact that their tumours depend on cholesterol to grow,” explained  Franks, adding that monitoring cholesterol levels in men at risk, diagnosed or treated for prostate cancer may help limit cancer growth or even recurrence.

“Our data show that increased plasma cholesterol levels and fat deposits caused by the consumption of a typical Western diet accelerates prostate tumor progression and exacerbates its aggressiveness in a mouse model of prostate cancer,” write the authors.  “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.”

The connection between cholesterol and tumours, they add, makes intuitive physiologically sense since cells need cholesterol to produce androgen hormones which promote prostate cancer growth, and furthermore tumours feed on cholesterol.

Reference

G Llaverias, C Danilo, Y Wang et al. A western-type diet accelerates tumor progression in an autochthonous mouse model of prostate cancer. The American Journal of Pathology. 2010. Doi: 10.2353/ajpath.2010.100568.