Strict diet may stop prostate cancer

A new study reveals that men with early-stage prostate cancer may be able to halt the progression of their disease by making substantial lifestyle changes such as adopting a very low-fat, vegan diet, exercising and meditating.

The authors of the study, published Thursday, August 11, in the Journal of Urology, say it is the first clinical trial showing that lifestyle changes can halt the progression of prostate cancer. The study could have implications for the more than 230,000 men who are diagnosed with prostate cancer each year.

Lead author Dean Ornish, a longtime crusader of ultra low-fat diets, said the study shows that adopting various lifestyle changes can be beneficial to men with prostate cancer in addition to whatever other conventional measures they take. Other study authors included researchers from UCSF and the Memorial Sloan-Kettering Cancer Center in New York.

Earlier epidemiological studies have linked various lifestyle measures such as a high-fat diet, especially animal fat, obesity and a lack of physical activity with an increased risk of developing prostate cancer.

There is hope that various dietary measures, such as eating fruits and vegetables or taking supplements such as lycopene, selenium and vitamin E, can lower risk, but that evidence still is insufficient, according to the National Cancer Institute.

There is some evidence that diets high in fat increase the risk of prostate cancer, and that certain foods -- such as broccoli, or the nutrient lycopene from cooked tomato products -- are protective.

The study involved 93 men with an average age of about 66 who were diagnosed by biopsies with low-grade prostate cancer. All of the men had decided to undergo so-called watchful waiting, which meant their cancer would be monitored but they would not immediately undergo conventional treatment such as surgery or radiation.

Forty-four of the men were put into an intensive intervention program. The other 49 men did not undergo intensive lifestyle changes. Researchers used the prostate-specific antigen, or PSA, test as a way to monitor the disease progression in the men. After one year, the men in the intervention program had an average 4 percent decline in their PSA test scores, compared with a 6 percent increase in the scores of the control group.

In another measure, six of the men in the control group went on to have surgery or some other treatment due to a progression of their disease, compared with none of the men in the intervention group.

In addition, blood samples were taken from the men to see if the serum could inhibit prostate cancer tumor growth in a laboratory dish. There was a 70 percent inhibition of tumor cell growth from the blood from the men in the intervention group, compared with 9 percent from the control group.

Howard Parnes, a physician with the National Cancer Institute, said the study's results appear to support the hypothesis that dietary and lifestyle measures can affect prostate cancer progression, "but there are a lot of caveats." One problem, he said, is that the PSA score, the primary measure in the study, is only a surrogate for disease progression. It is not a clinical outcome, such as mortality. The PSA score could have been affected by the soy, which has a weak hormonal affect, he said. In addition, there were so many variables in the study that it was impossible to sort out which ones may have caused the beneficial effects, he said.

In addition to lower PSA scores, the men in the intervention group lost an average of about 10 pounds and had significant improvements in their cholesterol levels.

In previous research, Ornish has showed that intensive intervention programs can reverse heart disease.

Here is the regimen researchers used on the men whose prostate cancer appeared to improve:

A low-fat, vegan diet, and daily tofu and soy supplements400 international units of vitamin E
Three grams of fish oil
200 micrograms of selenium
Two grams of vitamin C
30 minutes of moderate exercise six days a week
An hour a day of stress management with techniques such as meditation and yoga