Which urologist a patient with prostate cancer chooses may be more important in determining whether he receives hormone therapy than other factors such as his age or type of tumor, a new study reports.

"The urologist seems to play a role that is at least as important, if not more important, than tumor grade and patient characteristics," says lead researcher Dr. Vahakn B. Shahinian of the University of Texas Medical Branch in Galveston.

The findings suggest that a patient could go to two urologists and receive different opinions about whether to have the treatment, called androgen deprivation therapy because it blocks androgen hormones such as testosterone.

"This scenario is cause for concern because patients might be getting therapy that may not be in their best interest," says Dr. Shahinian.

Approximately half of all prostate cancer patients receive the therapy over the course of their disease. When given with radiation, the therapy can extend the survival of patients with locally advanced disease.

But there are not clear data for urologists to follow about when androgen deprivation therapy should be used for other patients. The treatment is expensive and potentially toxic, with side effects such as an increased risk of fractures and loss of sexual function.

During the 1990s, there was a dramatic increase in the use of androgen deprivation therapy for prostate cancer, even in cases where its benefit was unproven or highly improbable. This in part led to the new study.

The researchers linked the Surveillance, Epidemiology, and End Results (SEER) and Medicare databases to identify 1,800 urologists who treated 61,000 men diagnosed with prostate cancer at age 65 years or older. The most recent data were from 1999.

The urologist was responsible for about 20 percent of the variation in the use of hormone therapy, versus 10 percent for tumor grade and stage, and 4 percent for patient characteristics, according to findings in the June 21 Journal of the National Cancer Institute (JNCI).

Dr. Shahinian and his colleagues have begun to try to identify the characteristics of urologists that cause them to select the treatment.

A limitation of the study was the lack of information about prostate-specific antigen (PSA) levels in participants. Rising PSA levels can be an indication for the therapy, so some patients might have received it based on evidence rather than physician judgment.

Nonetheless, the study shows that a powerful anticancer therapy is often selected based on a physician's intuition rather than on hard facts or evidence-based medicine, says Dr. Paul Schellhammer of Eastern Virginia Medical School, who wrote an editorial in JNCI.

Prostate cancer is an extraordinarily heterogeneous disease, and many cancers are diagnosed that will not affect the length or the quality of a man's life. "But hormone therapy represents a powerful remedy for patients who have progressive disease," Dr. Schellhammer adds.

The challenge for physicians, he suggests, is to offer androgen deprivation therapy to men with high-risk, potentially lethal prostate cancer early in their course of treatment and to withhold it from men with low-risk disease, thereby avoiding unnecessary risks.

Clinical trials are under way to clarify the picture of how and when the therapy should be used. Dr. Schellhammer predicts that a day will come when the treatment's use is guided by physicians but based on evidence rather than directed by physicians, as it is today.

By Edward R. Winstead