Categorized | Prostate Health

Pomegranates and PSA Scores

Recent studies on the effects of pomegranate extract on prostate cancer have yielded mixed results. In one study, which focused on prostate-specific antigen levels, pomegranate extract slowed the PSA doubling time by more than 6 months in a broad population of patients with prostate cancer; however, some evidence suggests that it may accelerate the disease for some individuals.

Overall, the median pretreatment PSA doubling time (PSADT) increased significantly from 11.9 months to 18.5 months post treatment among 92 evaluable men with a rising PSA after primary therapy in the phase II, double-blind, multicenter study.

The increase in median PSADT was similar whether the men were randomized to one capsule daily (from 11.9 to 18 months) or to three capsules daily (from 12.2 to 17.5 months). A negative PSA slope, suggesting declining PSA values, was observed in 13% of patients, reported Dr. Michael Carducci, a professor of oncology and urology at Johns Hopkins University in Baltimore.

Nearly 20% of the population, however, had their PSADTs shortened, leading to treatment discontinuation.
“There is an apparent benefit across all PSA doubling times, although some shortening of PSA doubling time was seen,” stated Dr. Carducci at the Genitourinary Cancers Symposium.

Dr. Michael J. Morris of Memorial Sloan-Kettering Cancer Center in New York indicated that a more prospective evaluation of the study’s results was necessary.

“If you believe that prolonged PSA doubling time is clinically beneficial, what do we say about patients whose disease appears to accelerate as a result of taking the pomegranate extract?” he asked. “Do we say or suggest that a third to 40% of patients might be done some harm, or might have an earlier clinical end point? I don’t know, but I think that’s an issue of concern.”

One limitation of the pomegranate study, acknowledged by Dr. Carducci, is that it lacked a placebo. A number of reports in the literature, including studies of rosiglitazone (Avandia) and atrasentan (Xinlay), have shown that even a placebo can slow PSADT.

“We did not have a placebo, so [these data are not] definitive and could be explained by on-study regression to the mean,” he said, noting that data should be available in the near future from a 200-patient, placebo-controlled trial of pomegranate extract liquid.

Current laboratory data also shows that pomegranate extract is more effective at controlling the growth of prostate cancer than is pomegranate juice in prostate cancer cell lines, but this comparison has not been tested in patients, explained Dr. Carducci.

The 101 men in the intent-to-treat analysis had a medial Gleason score of 7, and about one-third of them had a baseline PSADT of 9 months or less. The men were treated for up to 6 months (92% of patients), 12 months (70%), or 18 months (36%) with capsules containing 1,000 mg of pomegranate juice. In all, 58% of patients completed the 18-month, double-blind portion of the study, and 42% discontinued treatment before progression.

Ultimately, the decision to use pomegranate extract or juice is a matter of discussion between physician and patient, concluded Dr. Carducci.

“I think with two consistent data sets showing slowing PSA doubling time, it would be reasonable for a patient to consider and understand what he’s getting himself into. It’s possible that patients with slower growing disease may have the greater benefit.”

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March 2011
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