The pomegranate extract effect … redux


According to an article just published in the journal Prostate Cancer and Prostatic Diseases, any effect of taking pomegranate extract in delaying prostate cancer progression over time after first-line treatment may be limited.

This randomized, double-blind, placebo-controlled, multi-institutional study (see NCT336934) was designed to investigate the effects of pomegranate liquid extract or juice on PSA doubling times in men with a rising PSA level after primary therapy for prostate cancer after 1 year of treatment and follow-up. The primary end point was therefore a change in serum PSA doubling time. However, other secondary endpoints were also expored.

Pantuck et al. now report the following results to date:

  • 183 patients were eligible for randomization.
  • Eligible subjects were randomly assigned to the active and placebo groups with a ratio of 2:1.
    • 102 patients were randomized to pomegranate extract.
    • 64 patients were randomized to a placebo.
    • 17 patients were randomized to pomegranate juice (although it’s not exactly clear why from the abstract).
  • For all men in the placebo group
    • Median PSA doubling time at baseline (prior to randomization) was 11.1 months.
    • Median PSA doubling time at 1 year on treatment was 15.6 months.
    • This difference was statistically significant (P < 0.001).
  • For all men being treated with either pomegranate extract
    • Median PSA doubling time at baseline was 12.9 months.
    • Median PSA doubling time at 1 year on treatment was 14.5 months.
    • This difference was not statistically significant (P = 0.13).
  • For all men being treated with pomegranate juice
    • Median PSA doubling time at baseline was 12.7 months.
    • Median PSA doubling time at 1 year on treatment was 20.3 months.
    • This difference was statistically significant (P = 0.004).
  • None of these changes were statistically significant between the three groups (P > 0.05).
  • For those men who were manganese superoxide dismutase (MnSOD) AA genotype positive
    • Placebo patients exhibited a 1.8-month change in median PSA doubling time from 10.9 months at baseline to 12.7 months (P = 0.22).
    • Patients treated with pomegranate extract exhibited a 12-month change in median PSA doubling time from 13.6 at baseline to 25.6 months (P = 0.03).
  • The majority of adverse events were of moderate or mild grade.

The authors draw three conclusions from this study:

  • “Compared with placebo, pomegranate extract did not significantly prolong PSADT in prostate cancer patients with rising PSA after primary therapy.”
  • “A significant prolongation in PSADT was observed in both the treatment and placebo arms.”
  • “Men with the MnSOD AA genotype may represent a group that is more sensitive to the antiproliferative effects of pomegranate on PSADT.”

The implication is that there may be some benefit to the use of pomegranate juice among men with prostate cancer who carry the MnSOD AA gene — but further studies would be needed to prove this. There appears to be no significant impact of pomegranate juice in other patients, based on this study.

3 Responses

  1. How does one get tested for “manganese superoxide dismutase AA….”?

  2. I have absolutely no idea … but presumably it can be done by selected laboratories.

  3. It’s just my opinion, but I think the MnSOD AA genotype subanalysis was a Hail Mary play. This is probably a very rare genotype and it is more than likely that if they had tested other antioxidants, soy isoflavones, smoking cessation, or even just exercise, they may have had similar findings. Pantuck’s lab has been trying to prove pomegranate efficacy since 2006, and when POM Wonderful tried to make claims about their pomegranate juice, they were challenged by the FDA to come up with a placebo-controlled trial. This is the result, unfortunately for them. I had always wondered why they didn’t have placebo controls in their earlier studies — it would have been so easy.

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