High cholesterol levels accelerate the growth of prostate tumours, research has found.
Prostate cancer can be a killer
A team from Boston's Children Hospital also found that cholesterol-lowering statin drugs may inhibit prostate cancer growth.
The findings may help explain why prostate cancer is more common in the West, where diets tend to be high in cholesterol.
Details are published in the Journal of Clinical Investigation.
Rates of prostate cancer in rural parts of China and Japan, where low fat diets are the norm, are up to 90% less than in the West.
Yet when Eastern men migrate to the West their chances of being diagnosed with prostate cancer increase.
This has led doctors to suspect that environmental factors - such as diet - may play a significant role in the development of the disease.
The Boston team injected human prostate cancer cells into mice and watched them grow.
When the animals were fed high cholesterol diets, cholesterol was found to accumulate in the outer membranes of tumour cells.
This appeared to alter chemical signalling patterns within the cells.
As a result, they resisted signals telling them to commit suicide and instead continued to proliferate in the uncontrolled fashion seen in cancer.
The increased cholesterol levels did not trigger new cancers in the mice.
But six weeks after the tumour cells were injected, mice on the high-cholesterol diets had twice as many tumours as animals on ordinary diets.
Their tumours were also much larger in size.
When the cells were exposed to the cholesterol-lowering drug simvastatin, cell death increased and tumours stopped proliferating.
But replenishing cell membranes with cholesterol caused the cancer to run out of control again.
Lead researcher Dr Michael Freeman said: "Our study opens up a new paradigm in thinking about how cancer might be controlled pharmacologically by manipulating cholesterol.
"Our data support the notion that cholesterol-lowering drugs - which are widely used and fairly safe - might be effective in prevention of prostate cancer, or as an adjunctive therapy."
Chris Hiley, of the UK Prostate Cancer Charity, said: "This research is clearly at an early stage, as it was accomplished in mouse cells, not men, but it's heartening to see a plausible connection made between processes inside cells and the Westernised high fat diet that seem to increase the risk of prostate cancer occurring.
"The results do open up thinking about new drug therapies.
"But there is also a low tech option any man could attempt today.
"Adopt a healthy low cholesterol diet and active lifestyle.
"Cut down on saturated fats, reduce the total amount of fat eaten but eat oily fish, and eat a high fibre diet - with porridge oats, and plenty of fresh fruit and vegetables."
Every year 27,000 men are diagnosed with prostate cancer and 10,000 men die from it.