More men with prostate cancer may be able to safely put off treatment in favor of monitoring the disease over time, a study of patients at one U.S. medical center suggests.

Researchers found that among 466 prostate cancer patients who opted for "active surveillance" rather than immediate treatment, those with tumors at intermediate risk for progression fared as well over four years as their counterparts with low-risk prostate cancer.

The findings, reported in the Journal of Clinical Oncology, suggest that while active surveillance is typically only offered to men with low-risk prostate cancer, it may be a reasonable choice for certain men with intermediate-risk disease as well.

The issue is important because increasingly, experts are calling for expanded use of active surveillance, sometimes called watchful waiting, in managing prostate cancer.

Unlike many other cancers, prostate cancer is often slow-growing and in many cases may never progress to the point where it threatens a man's life. This complicates treatment decisions, because surgery and other therapies for prostate cancer carry risks, including long-term urinary incontinence and erectile dysfunction. So for many men, treating the disease could potentially do more harm than good.

But the advent of prostate cancer screening with PSA (prostate-specific antigen) testing has meant that a large number of U.S. men are now diagnosed with early-stage cancer with a low risk of progression (low-risk disease).

According to the National Cancer Institute, about half of the more than 190,000 U.S. men diagnosed with prostate cancer in 2009 would fall into this low-risk group.

The proportion of cancers that fall into the intermediate-risk category varies depending on the precise definition of "intermediate," but a good estimate is somewhere between 25 percent and 40 percent, according to Dr. Matthew R. Cooperberg, an assistant professor of urology at the University of California, San Francisco (UCSF), and the lead researcher on the new study.

Right now, men with low-risk prostate cancer can choose to forgo immediate treatment in favor of active surveillance. In these cases, treatment is deferred and the disease is instead monitored with regular PSA blood tests, digital rectal exams and possibly prostate biopsies.

But whether some men with intermediate-risk prostate cancer can safely opt for active surveillance has been largely unclear. And active surveillance is rarely presented to them as an option, Dr. Peter Carroll, chair of the UCSF department of urology and the senior researcher on the study, told Reuters Health in an e-mail.

In general, low-, intermediate- and high-risk prostate cancers are defined by factors including the stage of the disease, the level of PSA (prostate-specific antigen) in the blood and Gleason score -- a measure of a prostate tumor's aggressiveness.

The men in the current study were all treated at UCSF and had opted for active surveillance, which included PSA tests and digital rectal exams about every three months, ultrasound tests every six to 12 months, and biopsies every one to two years.

Of the patients, 376 had low-risk cancer and 90 had intermediate-risk.

Over four years, 61 percent of the intermediate-risk patients and 54 percent of the low-risk group saw no growth in their tumors despite not getting treatment. The difference between the two groups could easily have been due to chance.

The proportion of men who opted to start treatment during the study period was also similar -- 30 percent of low-risk patients and 35 percent of intermediate-risk.

Surgery was the most common treatment. Of those who had surgery, none had seen their cancer spread to nearby lymph nodes. In addition, none had a rise in PSA, which can indicate that the cancer has come back, within three years of surgery.

The study has its limitations, including the fact that all of the patients were treated at one medical center, so the findings may not extend to patients elsewhere, Carroll said.

He also stressed that active surveillance would be an option only for carefully selected men with intermediate-risk cancer.

"Such patients require careful evaluation and an assessment can be made only on the basis of a very well performed biopsy and by experienced clinicians," Carroll explained.

Among the best candidates for active surveillance, according to Carroll and Cooperberg, are men with a limited life expectancy, which is not just a matter of age, but also overall health. In general, men with chronic medical conditions like heart disease may simply not live long enough to reap any benefits from prostate cancer treatment, but could suffer the harms.

For now, Carroll said, the take-home message for men with prostate cancer is that they should not "rush" into treatment, but seek opinions about all of their options, including active surveillance.
Carroll and Cooperberg both noted that they believe that PSA screening has saved lives by allowing more men to be diagnosed when prostate cancer is curable.

But that has come at the price of a great deal of "overtreatment." (The downsides of PSA screening are why the American Cancer Society and other medical groups do not recommend routine screening, but instead advise men to talk with their doctors about the pros and cons.)
"Men with high-risk disease clearly benefit from early and aggressive treatment," Cooperberg noted, "whereas those with low-risk disease often do not."

The current study, he said, "suggests that the optimum risk threshold for triggering treatment may be blurrier than previously thought."