February 6, 2009

From Prognosis to Pomegranates—Studies Tackle Early Prostate Cancer

Early prostate cancer refers to cancer that is confined to the prostate. Although many men with early prostate cancer are successfully treated with local therapies such as surgery and/or radiation therapy, some men will eventually experience a cancer recurrence. Recent studies clarify the prognosis of men with early prostate cancer, and one study suggests a novel approach to slowing the progression of prostate cancer.

To describe the survival and recurrence rates among men treated with radical prostatectomy, researchers reviewed long-term data from 787 men who had been treated between 1945 and 1994.[i] Roughly half the patients had cancer that was confined to the prostate. The remaining men had cancer that had spread only to nearby tissues.

In addition to survival, the researchers assessed the frequency of increasing levels of prostate-specific antigen (PSA) following surgery, as well as local and distant cancer recurrence.

  • After an average of 12 years of follow-up, 31% of men had experienced a rise in PSA levels; 8.4% had experienced a local cancer recurrence; and 11% had experienced a distant cancer recurrence.
  • By 25 years after surgery, the probability of death due to prostate cancer was 19%.

This study provides reassuring evidence that the risk of death from prostate cancer remains low following radical prostatectomy.

A second study addressed treatment outcomes among men who received additional treatment because of a PSA increase following local therapy.[ii] The study involved 67 men who had undergone either radical prostatectomy or radiation therapy for early prostate cancer. All of the men had experienced a PSA increase after local therapy and had a short PSA doubling time (PSA levels doubled within six months). As a result of the PSA increase, the men were treated with androgen deprivation therapy.

  • PSA nadir (the lowest PSA level achieved) after androgen deprivation therapy was an important predictor of survival. Men whose PSA level remained above 0.2 ng/mL after androgen deprivation therapy were eight times more likely to die of prostate cancer than men who achieved lower PSA levels.
  • Gleason score was also an important predictor of survival. Men with a Gleason score greater than seven were five times more likely to die of prostate cancer then men with a lower Gleason score.
  • Among men who had both a low PSA nadir and a low Gleason score, the probability of dying of prostate cancer over a three-year period was 3.6%. Among men who had a high PSA nadir and a high Gleason score, the probability of dying of prostate cancer over a three-year period was 73.3% (this estimate has some uncertainly because only a small number of study subjects fell into this category).

The researchers conclude that Gleason score and PSA nadir after androgen deprivation therapy may help identify patients who are at increased risk of death from prostate cancer. The researchers note that high-risk patients may be good candidates for clinical trials evaluating new therapeutic approaches.

Finally, a third study suggests a novel (but still unproven) approach to slowing the progression of early prostate cancer.[iii] The study enrolled 48 men who had increasing PSA levels following surgery or radiation therapy. The men had PSA levels between 0.2 and 5 ng/mL and Gleason scores of seven or less. The men were given eight ounces of pomegranate juice per day. After the men began taking the pomegranate juice, their average PSA doubling time increased from 15 months to 54 months, suggesting that the rate of PSA increase had slowed. Because this study was small and did not include an untreated comparison group, these results will need to be confirmed by other studies.

[i]Porter C, Kodama K, Gibbons R, et al. 25-Year Prostate Cancer Control and Survival Outcomes: A 40-Year Radical Prostatectomy Single Institution Series. Journal of Urology. 2006; 176: 569-574.

[ii]Rodrigues N, Chen M-H, Catalona W, et al. Predictors of Mortality after Androgen-Deprivation Therapy in Patients with Rapidly Rising Prostate-Specific Antigen Levels after Local Therapy for Prostate Cancer. Cancer. 2006; 107: 514 – 520.

[iii]Pantuck AJ, Leppert JT, Zomorodian N, et al. Phase II study of pomegranate juice for men with rising prostate-specific antigen following surgery or radiation for prostate cancer. Clinical Cancer Research. 2006;12:4018-4026.

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Tags: Prostate Cancer, Uncategorized