Health - Index
Lifestyle changes may halt prostate cancer, study says
BY JOHN FAUBER
Aug 10, 2005
MILWAUKEE - (KRT) - A provocative new study suggests that men with early-stage prostate cancer who elect not to undergo conventional treatment 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 in the Journal of Urology, say it is the first randomized clinical trial showing that lifestyle changes can halt the progression of prostate cancer.
However, urologists not associated with the research said the length of the study was too short, the number of men too few and the outcome measures too imprecise to make definitive conclusions about the benefits of the intervention.
In addition, maintaining the strict diet used in the study would be very difficult for many men, they said.
"I don't know if Draconian is the word," said William See, chairman of the urology department at the Medical College of Wisconsin. "(But) the ability of the average Midwesterner to tolerate that kind of diet is questionable."
The study comes at a time when there is growing controversy about the best way to treat early-stage, localized prostate cancer. The study and additional research that may stem from it could have implications for some of the more than 230,000 men who are diagnosed with prostate cancer each year. African-American men have a 60 percent higher risk of developing prostate cancer than whites, and are twice as likely to die of the disease.
Lead author Dean Ornish, director of the Preventive Medicine Research Institute in Sausalito, Calif., and 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.
"(Improved) diet and lifestyle play a role in the progression of prostate cancer and the only side effects are good ones," said Ornish, a controversial author and clinical professor of medicine at the University of California, San Francisco.
Other study authors included researchers from UCSF and the Memorial Sloan-Kettering Cancer Center in New York.
"This is the first in a series of trials attempting to better identify the exact role of diet and lifestyle in the prevention and treatment of prostate cancer," senior author Peter Carroll, chairman of the urology department at UCSF, said in a statement.
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.
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 that included a low-fat, vegan diet, and daily tofu and soy supplements, as well as 400 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, and an hour a day of stress management with techniques such as meditation and yoga.
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.
"We are learning more and more about compounds that may prevent, if not have therapeutic potential in prostate cancer," said Jason Gee, a urologic oncologist at the University of Wisconsin Hospital in Madison. "In a select group of patients who are appropriate for watchful waiting, some dietary changes may be helpful as suggested by this study."
However, Gee said it was too early to make overall recommendations based on the study, which needs to be validated by further research.
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.
"To say to patients, `You've got to do all these things' puts a large burden on them and creates a lot of guilt and stress," said Parnes, chief of the prostate and urologic cancer research group in the division of cancer prevention at the cancer institute.
"I don't think we should tell people you should do this."
However, he said the study was a step in the right direction.
"This kind of work does stimulate the research field to look at dietary and lifestyle measures," 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 earlier research, Ornish has showed that similar 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 supplements
400 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