February 6, 2009

Predicting Prostate Cancer Prognosis

Some prostate cancers are slow-growing and unlikely to cause health problems during a man’s lifetime, while others are more aggressive. In order to provide more individualized treatment for prostate cancer, researchers continue to look for cancer characteristics that will allow them to distinguish between faster and slower growing cancers. Men with more aggressive cancer may benefit from more intensive treatment.

Two studies evaluated factors that were linked with prostate cancer recurrence, metastasis (spread), or death. If confirmed, the results of these studies may help healthcare professional identify men with life-threatening prostate cancer.

Rate of PSA Increase

The first study evaluated the rate of prostate-specific antigen (PSA) increase many years before prostate cancer diagnosis.[1] Prostate-specific antigens are proteins that are normally shed by the prostate into the bloodstream. Elevated PSA levels may indicate the presence of prostate cancer and response to therapy. A question that remains uncertain, however, is whether the rate of PSA increase can be used to identify potentially life-threatening prostate cancer during a period when the cancer is still curable.

To address this question, researchers evaluated information from the Baltimore Longitudinal Study on Aging. The researchers evaluated PSA histories in three groups of men: men without a diagnosis of prostate cancer; men who had died of prostate cancer; and men who had been diagnosed with prostate cancer but were still alive or had died of another cause.

  • The rate of PSA increase 10–15 years before diagnosis (when most men had PSA levels under 4 ng/mL) was linked with the likelihood of prostate cancer death. The rate of PSA increase during this time period was higher among the men who eventually died of prostate cancer than among the men without prostate cancer or the men who had prostate cancer but did not die of it.
  • Men whose PSA increased by more than 0.35 ng/mL per year during the 10–15 years before diagnosis were more than four times more likely to die of prostate cancer than men with a lower rate of PSA increase.

The researchers conclude that “PSA velocity [rate of increase] may help identify men with life-threatening prostate cancer during a period when their PSA levels are associated with the presence of curable disease.”

Another Protein Indicates Prognosis

The second study assessed levels of a particular protein (zinc-alpha2-glycoprotein, or AZGP1) in early-stage prostate cancers removed by prostatectomy.[2] The researchers evaluated whether levels of this protein were linked with the likelihood cancer recurrence, metastasis, or death.

  • Low AZGP1 levels were associated with a nearly fivefold increased risk of cancer recurrence.
  • Low AZGP1 levels were associated with an eightfold increased risk of developing metastases to the bone or death from prostate cancer.

If confirmed, these results suggest that AZGP1 levels in cancer tissue removed by prostatectomy may provide valuable information regarding a patient’s prognosis and need for aggressive treatment. An advantage of this marker is that it could be assessed early—immediately after the patient undergoes surgery for prostate cancer.

These and other similar studies are building our understanding of how particular prostate cancers are likely to behave. Eventually, this may allow for more individualized prostate cancer treatment.


[1] Carter H, Ferrucci L, Kettermann A, et al. Detection of Life-Threatening Prostate Cancer With Prostate-Specific Antigen Velocity During a Window of Curability. Journal of the National Cancer Institute. 2006; 98: 1521-1527.

[2] Henshall S, Horvath L, Quinn D, et al. Zinc-alpha2-glycoprotein Expression as a Predictor of Metastatic Prostate Cancer Following Radical Prostatectomy. Journal of the National Cancer Institute. 2006; 98:1420-1424.

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Tags: Prostate Cancer, Uncategorized