TUESDAY, Nov. 14, 2006 (HealthDay News) -- A series of studies in this week's Journal of the American Medical Association offers good news to men battling prostate cancer or concerned about healthy prostate function.
One trial found that the use of radiation therapy after prostate removal improves results for men at high risk for prostate cancer recurrence.
"The benefit of adjuvant radiation is now confirmed in prostate cancer, like it is in many other cancers. Finally, we have the data to show that these patients can be helped further after their surgery," said Dr. Gregory Swanson, associate professor of radiation oncology at the University of Texas Health Science Center, San Antonio.
A second study, focused on the biology of prostate tissue in older men, found that links between testosterone replacement therapy (TRT) and prostate cancer "may not be as great as once feared," according to the trial's lead author, Dr. Leonard Marks, medical director of the Urological Sciences Research Foundation in Culver City, Calif. His team found no changes in the prostate tissue of older men after six months of TRT.
Both researchers presented their findings Tuesday at an American Medical Association news briefing in New York City that was timed to the release of the Nov. 15 issue of JAMA, which is focused on men's health.
Despite advances in early detection and treatment, prostate cancer remains a leading killer of American men. Most fatal cases of the disease occur when it is allowed to migrate beyond the gland, sparking disease recurrence.
According to Swanson, about one-third of the 230,000 new prostate cases diagnosed in the United States each year are treated with radical prostatectomy -- surgical removal of the organ. In up to half of those cases -- 30,000 men -- post-surgical tests reveal traces of lingering cancer cells that boost the risk of a recurrence.
Post-surgical ("adjuvant") radiation has a long record of "mopping up" these stray cells and improving the survival of patients with other types of cancer. However, the jury has been out as to whether the same might be true for prostate cancer.
In its study, the largest and longest of its kind to date, Swanson's team compared 10-year outcomes in a group of 425 older prostate cancer patients who had undergone radical prostatectomy but who still showed suspicious cells in the surrounding margins. His group randomly assigned half of the men to adjuvant radiation therapy, while the other half did not receive the treatment.
Ten years later, 35.5 percent of men who received radiation had developed fatal or nonfatal metastatic disease, compared to 43 percent of those who didn't get irradiated. Overall survival rates were similar between the two groups -- 71 of 214 men who received radiation died vs. 83 of 211 men who did not get the treatment.
Both of these results came very close to -- but did not meet -- so-called statistical significance, meaning that definite proof of treatment benefit is still lacking. However, Swanson believes "there is a compelling, although not conclusive" trend toward better survival in the irradiated group.
He also noted that about one-third of patients in the group who originally did not receive radiation eventually did receive it once they encountered a recurrence.
"People recognized that there was a benefit to radiation and said, 'Let's treat those patients,' " Swanson said. This probably caused more patients in the control group to survive than normally would have, confounding the results, he said.
Swanson said changes in other prostate cancer "markers" -- such as elevated blood levels of prostate specific antigen (PSA), a harbinger of cancer -- did meet statistical significance and were much more prevalent in men who did not undergo radiation, compared with those who did. Men who did not have radiotherapy were also 38 percent more likely to suffer disease recurrence that those who had had the adjuvant therapy, the study found.
The bottom line, according to Swanson: "The message to the urological community is that, yes, your patients will do better [with radiation] than with just surgery alone."
Prostate cancer risk was the focus for Marks' group of researchers, as well. He said recent media hype on the power of testosterone to boost aging males' libido and muscle tone have pushed annual U.S. sales of testosterone replacement therapy (TRT) to more than $700 million.
However, doctors have long known that testosterone can also raise a man's risk for prostate malignancy. So, Marks' team decided to look at the biological effect of six months of standard TRT, given in injections every two weeks, on the prostate tissue of 44 men ranging from 44 to 78 years of age.
All of the men had relatively low levels of circulating testosterone upon entering the study, with no sign of prostate malignancy. Forty of the men agreed to provide the researchers with prostate tissue biopsies at the beginning and end of the six-month trial.
The researchers said they found no detectable change in prostate tissue after six months of TRT, despite the fact that the therapy caused blood levels of circulating testosterone to rise to mid-normal levels. Concentrations of male hormones in prostate tissues differed only slightly after therapy, and the team saw no changes in cells -- for example, alterations in gene expression or cell proliferation -- that might point to an increased risk for cancer.
While this is good news for men who are taking or might take TRT, Marks stressed that the study only examined the prostate tissue biology of a select group of men with no prior signs of cancer.
"These data do not assure prostate safety for populations of older men harboring highly prevalent subclinical disease," said Marks, who is also clinical professor of surgery/urology at the University of California, Los Angeles. "We know that if you do thorough studies of the prostate glands of aging men, microscopic [traces] of cancer are present in many of them."
So, while this tissue sampling of 44 men found testosterone therapy to have no cancer-promoting effects, those results might not be borne out in larger epidemiological studies, he said. Until such studies are done, Marks said, "My concern is that some physicians may misinterpret these data and start using testosterone willy-nilly. My hope is that it won't be used that way."
A third study in the same issue of JAMA offered some guidance to millions of men bothered by urinary incontinence triggered -- at least in part -- by an enlarged prostate.
The study of more than 700 men found that a combination of two widely used medications, tolterodine (Detrol LA) and tamsulosin (Flomax), worked better in combination at reducing urinary trouble than either drug alone.
"In those men who don't respond to a single therapy -- and that's a host of men -- we're able to now, with this combination, provide a real improvement in their quality of life," said lead researcher Dr. Stephen Kaplan, professor of urology at Weill Medical College of Cornell University, in New York City.
Find out more about prostate health at the U.S. Food and Drug Administration.