The debate about the value of screening for early detection of prostate cancer continues unabated. In fact, studies conducted in both the United States and Europe have found that there are limited advantages to routine prostate cancer screening, particularly in light of the fact that the cancer is so slow growing, there is no lifesaving advantage for patients who undergo surgery. Furthermore, the treatment itself can cause impotence and incontinence. However some prostate cancers are life-threatening and require aggressive treatment.
Now, a new study has identified three molecules that appear to be associated with more aggressive prostate cancers and might provide biomarkers that could help healthcare providers distinguish which cancers grow so quickly that treatment is required. Specifically, researchers from the Veterans Affairs Connecticut Healthcare System examined tissue samples from 1,172 men with prostate cancer. The participants were being treated at VA facilities throughout New England. From a number of potential markers, the investigators identified three that were associated with a higher risk of death from cancer. These included bcl-2, a molecule that helps regulate cell death; p53, a protein produced by a tumor-suppressor gene; and microvessel density, the excessive production of blood vessels needed for growth of a cancer. Levels of all three were found to be significantly higher in those men who died of prostate cancer 11 to 16 years following diagnosis.
“Measuring levels of the markers might someday help guide treatment of men with prostate cancer,” says study author Dr. John Concato, a professor of medicine at Yale University and director of the clinical epidemiological research for the Veterans Affairs Connecticut Healthcare System. “If the markers are positive, that might be an indication that more aggressive therapy is indicated.” Concato adds that this is just the first step in using biomarkers to guide treatment. “Other groups should replicate our results. Based on these results, there should be an effort at developing therapies that attack the mechanisms reflected by these markers.” Concato has proposed a clinical trial that “would treat patients based on marker status, as positive or negative.”
However, the study’s findings were challenged by Dr. Edward P. Gelmann, chief of the division of hematology/oncology and deputy director of the Herbert Irving Comprehensive Cancer Center at Columbia University. Dr. Gelmann suggests that the results “are not reproducible from one laboratory to the next. And there is a great variability in both technique and results.” However, as Dr. Concato points out, “We’re not trying to say these are the only markers. This is a proof of principle.” The study findings were published in the May 5 issue of the Annals of Internal Medicine.
News Release: Biomarkers may predict aggressiveness of prostate cancer www.health.usnews.com May 5, 2009
