Lifestyle Changes May Prevent or Reverse Prostate Cancer

Wednesday, April 30th 2003

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A healthy lifestyle involving a low-fat diet, exercise, and other factors may help stop or even reverse the progression of prostate cancer in men undergoing watchful waiting, according to the findings of the first randomized controlled clinical trial on the subject.

The research was conducted by Dean Ornish, MD, clinical professor of medicine at the University of California, San Francisco, and author of several popular books on the benefits of a low-fat diet for reversing heart disease.

Dr. Ornish and colleagues presented their findings at the American Urological Association annual meeting here.

The researchers randomized 87 men with biopsy-documented prostate cancer to an experimental group or a nonintervention control group. Men all had prostate-specific antigen (PSA) levels of 4 to 10 ng/mL and Gleason scores of less than 7.

The experimental group ate an entirely plant-based low-fat diet that emphasized unprocessed whole foods. Of the total calories, 70% came from complex carbohydrates and 20% came from protein, a large proportion of which was from soy. Participants also engaged in moderate aerobic exercise, stress management, and psychosocial group support. All men had declined conventional treatment.

The men were followed for one year, during which time PSA was measured twice at the beginning and then once every three months.

Mean PSA levels decreased by 5% in the experimental group after three months but increased by 1% in the control group (P = .045). Similarly, after one year, mean PSA levels decreased by 3% in the experimental group but increased by 7% in the control group (P = .034).

They found that changes in PSA at both three months (P = .047) and one year (P = .007) were directly correlated with adherence to the diet and lifestyle intervention. "The control group was following the diet 75% as well as the experimental group, yet their PSA rose," the authors note.

The researchers also evaluated the growth of the prostate cancer cell line LNCaP after they had added serum from patients. They found that growth was inhibited by 67% in the experimental group compared with 12% in the control group.

"It is possible that lifestyle changes may have affected the production of PSA without affecting the underlying prostate cancer," Dr. Ornish told Medscape, "but the direct inhibition of LNCaP cells argues against that," he added.

Dr. Ornish also pointed out that migrant studies have shown that when people eating a predominantly plant-based diet move to the U.S., their rates of prostate cancer increase dramatically. By comparison, the incidence of microscopic prostate cancer shows little variation worldwide, suggesting that a high intake of dietary fat and/or animal protein may help promote clinically significant prostate tumors.

The study size was not large enough to determine the relative contribution of each component of the intervention, he noted. But he suggested that urologists might consider recommending that patients make comprehensive changes in diet and lifestyle, regardless of whether a patient decides to undergo conventional treatment.

He added that comprehensive changes in diet and lifestyle might also reduce the risk of recurrence in patients who do undergo conventional treatment.

"The study addresses an important question that many doctors and patients are concerned about," Philip Belitsky, MD, professor in the Department of Urology at the Dalhousie University in Halifax, Nova Scotia, Canada, told Medscape.

According to Dr. Belitsky, many of the prostate cancer patients he sees ask about changes they can make in their lifestyle, and many have already made important lifestyle changes.

"This is the first systematic attempt I've seen in trying to address this issue, and I think this study will be seen as a precursor to many larger studies addressing it in a more systematic way," he said.

The study was privately funded.

AUA 98th Annual Meeting: Abstract 105681. Presented April 27, 2003.

Reviewed by Gary D. Vogin, MD

 

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