While prostate removal cures most men of their prostate cancer, more than a third show a rise in their prostate specific antigen levels in the 10 years following surgery, an early sign that cancer may be returning. Now, in the largest and longest study of its kind, urologists at Johns Hopkins have developed a simple method for assessing the risk these men have for developing deadly metastatic cancer.

"The first thing patients want to know after their PSA rises following surgery is how long they have to live," says Patrick Walsh, chief of urology, who removed the prostates of the 2,000 patients in the study. "And the first thing doctors want to know is what type of follow-up treatment the patient needs. Up until now, there hasn't been any sure way to know."

In the most extensive follow-up study on the natural course of prostate cancer after surgery, Walsh and his colleagues compiled 10,000 patient-years of data from 1982 to 1997; the men were followed for an average of 5.3 years. From this information, they developed a chart that physicians and patients can use to pinpoint the risk for developing metastatic cancer, which typically invades the bones of men with prostate cancer.

"Doctors used to say, 'You've recurred, but we aren't sure what that means,' " says Alan Partin, a co-author on the study, which appears in the May 5 Journal of the American Medical Association. "Now they can say, 'You've recurred, and we know your risk for developing advanced cancer.'"

The chart places men into different risk groups using three common measures: the so-called Gleason score from the removed prostate, timing of the rise in PSA level and the length of time it took the PSA level to double.

A man in the lowest risk group (with a moderately severe tumor, PSA recurrence after two years post-surgery and PSA doubling time greater than 10 months) has a 95 percent chance of being metastases-free three years after the PSA recurrence, an 86 percent chance at five years and an 82 percent chance at seven years.

"When men see their PSA levels rise again, they think that means the cancer is back and they need to get treated aggressively right away. But that isn't always the case," says Mario Eisenberger, an oncologist and study co-author. "This information will better equip doctors and their patients to decide who is a candidate for additional therapy."

The study is critical for future drug research as well, says Partin, because it provides essential baseline data. "Before, it was difficult to know if a drug was helping because you couldn't be sure what the disease would have done on its own," he says. "Now, researchers can compare their treatment groups with our study group and tell if their treatment is improving survival."

Other findings from the study:

* Men who experienced rising PSA levels (304 out of 1,997) remained free from metastatic cancer an average of eight years.

* After developing metastatic cancer, the average time to death was five years. However, men who developed metastases eight or more years following surgery had a much better outlook.

* At 15 years post-surgery, a projected 82 percent of men will still be free from metastatic cancer and considered cured.