National working group recommends efficacy be proven before trial progresses
NEW YORK, February 1, 2004 -- An abnormal or rising prostate specific antigen (PSA) blood test is often the first indication that a man may have prostate cancer. Even after diagnosis, the test continues to play a role in monitoring disease progression and assessing treatment outcomes. However, after a man has received curative therapy, there is uncertainty about what the PSA measurement means since the relationship of tumor mass and PSA value is less established at this time.
In an effort to resolve some of the treatment issues for the approximately 50,000 prostate cancer patients who will relapse each year, a national working group was organized by investigators from Memorial Sloan-Kettering Cancer Center, the National Cancer Institute, and the Prostate Cancer Foundation. The group has developed guidelines to define which patients should participate in a clinical trial and what compounds are appropriate for these studies. They recommend limiting treatment to patients who are at expected risk for developing metastatic disease. In addition, the group recommends that the only drugs that should continue to be evaluated in trials are ones that have demonstrated sufficient clinical activity as measured by a stabilized or declining PSA for a sufficient number of patients in a specified time. The Working Group's recommendations are published in the February 1, 2004 issue of The Journal of Clinical Oncology.
"We have not had good clinical models to help us predict whether the prostate cancer patient with a rising PSA after a radical prostatectomy or radiation therapy should be treated or observed," explained Dr. Howard Scher, Chief of the Genitourinary Service at Memorial Sloan-Kettering and first author of the study. "These guidelines will help standardize patient selection for a clinical trial, allowing us to tell a patient that a particular therapy is worth pursuing and what it will do for him in relation to his disease."
The working group looked at a patient population of men who had been previously treated for localized prostate cancer with either a radical prostatectomy or radiation therapy but now had a rising PSA, indicating treatment had failed. These men fall into two main categories. One is men whose rising PSA will not turn out to be clinically significant. Since they are not likely to die from their disease, treatment could actually be detrimental and shorten survival. The other sub-set is men whose rising PSA marks the onset of progression to metastatic disease. These patients have a systemic recurrence and a defined risk of developing clinically detectable metastases. Because early therapy may be life-saving for them, the Guidelines limit participation in clinical trials solely to these patients.
The Guidelines also have clinical trials criteria. Only therapies that have shown to be effective in advanced disease in other tumors and /or shown to affect a target or pathway known to contribute to prostate cancer progression should be studied. To move a drug forward, the trial should demonstrate that a significant proportion of patients had a decline or no increase in PSA and have prostate-cancer specific survival or extension of the time to development of metastatic disease. Drugs that cannot pass this high bar should not continue to be tested as a single agent but can be looked at in combination with other drugs.
"We hope that by creating a uniform system for evaluating treatments in patients with recurrent prostate cancer, we will be able to improve our understanding of the clinical course of the disease, and offer our patients treatments that are effective," explained Dr. Scher.
Source: Eurekalert & othersLast reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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