Prostate Cancer Studies Break New Ground
October 01, 2008
Three studies examining men with prostate cancer offering insight into hormones, radiation and a protective ingredient in wine, were presented recently at the 50th annual meeting of the American Society for Therapeutic Radiology and Oncology (ASTRO) in Boston.
The first was a novel trial whose findings ran counter to medical practice and suggested that testosterone may be protective against high cholesterol, heart attack and diabetes. The study found that men over 70 with early-stage prostate cancer were 20 percent more likely to die if they were treated with anti-androgen therapy before receiving radiation seed implants, compared to men who were treated with seed implants alone.
"While multiple studies have shown that eliminating androgens from the body benefits high risk and intermediate risk patients, this may not be the case for older men with low-risk prostate cancer," Amy Dorsoretz MD, lead author of the study and radiation oncology resident at the Harvard Radiation Oncology Program told DOTmed News.
She said it looks as if depleting a man's testosterone can adversely affect cholesterol levels, may cause diabetes, and may also lead to cardiovascular disease. Dorsoretz said that other studies have already shown that patients who are deprived of androgens experience changes in body fat and may be at risk for diabetes.
"In men under 70, we didn't see this," she said, noting that her study looked at men with low-risk cancers, whose cancers have not yet spread. "In patients with more aggressive cancer, the benefits of eliminating androgens from the body outweigh the risk, because depriving the body of androgens slows the progression of cancer....However, in low risk patients [with early-stage cancers], we found that there is no proven benefit from androgen deprivation therapy. When treating a man over 70, doctors should think carefully about the risk and benefits of hormone-deprivation therapy to their patients," Dorsoretz said.
She added that her study was a retrospective review, not a randomized trial and that conclusions in retrospective studies may have biases. "Randomized trials are hard to do--the cost is huge," Dorsoretz said, voicing a common research dilemma. "Also, patients must be willing to be randomized, but no one wants to flip a coin and choose their treatment on this basis, so we have to make due with retrospective studies."
Other Recent Relevant Studies
Another study, from Sweden, which was randomized, found that men with locally advanced prostate cancer who received radiation treatment along with anti-androgen therapy, improved their chances of living by 50 percent compared to those patients who received anti-androgen hormone treatment alone.
Anders Widmark, from Umea University in Umea Sweden, said that this trial is the first to show that men with locally advanced prostate cancer--cancer that has grown close to the border or outside the prostate gland to neighboring tissue--will survive substantially longer when radiation is added to their treatment plan.
The study involved 880 patients who were randomly assigned to receive three months of intense hormone therapy (temporary castration) combined with radiation therapy between February 1996 and December 2002.
Dr. Widmark found that 18 percent of patients who underwent hormone therapy alone died of prostate cancer during this time, compared to nine percent of those who had both hormone and radiation treatment.
Commenting on the Widmark study, Dr. Dorsoretz told DOTmed that unlike her study, "This study was focused on intermediate and high-risk patients.
What is more, she said that in the U.S., radiation therapy for prostate cancer patients is standard, so a study of this kind would never have been conducted.
She told DOTmed News that doctors in the U.S. began using radiation seed implants in the 1980s, but in Europe, the practice is still not widespread. She also noted that the virtue of the Swedish study is that was randomized.
A Third Study Looks at Wine
Meanwhile, a third study presented at the ASTRO meeting found that an antioxidant ingredient in red wine and fruit may protect people against radiation exposure.
Tests in mice showed that a substance called resveratrol, when altered using a compound called acetyl, could prevent some of the damage caused by radiation in a nuclear emergency, Dr. Joel Greenberger, a radiation oncologist at Johns Hopkins University, told physicians at the meeting.
"Currently there are no drugs on the market that protect against or counteract radiation exposure," he said in a statement. "Our goal is to develop treatments for the general population that are effective and non-toxic."