A landmark study of one the most agonizing decisions faced by men with early prostate cancer (search) — Should I have surgery? Or should I wait and see if it spreads? — found that for those under 65, operating clearly saves lives, cutting the death rate by more than half.

For men over 65, however, the jury is still out. These men account for the vast majority of prostate cancer patients.

Because of the findings, younger men "are much less likely to be encouraged to watch and wait," said Dr. Durado Brooks, director of prostate cancer at the American Cancer Society (search).

Prostate cancer is the second-most common type of cancer in American men, after skin cancer (search). About 232,000 new cases and 30,000 deaths are expected this year in the United States, according to the cancer society.

Often, doctors recommend "watchful waiting," because in many men, the tumor grows so slowly that they die of something else before the cancer ever kills them. Also, surgery to remove the diseased prostate carries its own risks: impotence and incontinence.

The latest study, published in Thursday's New England Journal of Medicine, followed Scandinavian men under age 75 for a decade after surgery, an unusually long period for such research. Overall, it found that surgery reduces deaths from any cause — not just cancer of the prostate — by nearly half.

About 9.5 percent of those who got surgery and 15 percent of those in the watchful waiting group died within 10 years of being diagnosed. But all the benefit appeared to be among men under 65, where the watchful waiting group had more than double the death rate of the surgery group.

The lead author of the study, Dr. Anna Bill-Axelson of University Hospital in Uppsala, Sweden, said urologists who favor surgery over watchful waiting will now be able to say that in younger men, "there is finally proof it saves lives."

Surgery "is ideal for the patient who is curable and going to live a long time," said Dr. Patrick Walsh, a professor of urology at Johns Hopkins Medical Institutions who in 1982 invented a nerve-sparing type of prostate surgery that sharply reduces chances of impotence and incontinence.

Prostate cancer strikes one in six American men during their lifetime, killing one in 33.

About 60,000 Americans undergo prostate cancer surgery each year. A man's age, his overall health, how advanced the cancer is and how aggressive it appears under the microscope are among the factors doctors use in deciding whether to recommend surgery.

But some recent research has shown that even slow-growing tumors can become more lethal after 15 years.

The latest study began in 1989. Researchers at 14 hospitals in Sweden, Finland and Iceland studied 695 men, most of them with tumors that had not spread beyond the prostate and were considered moderately aggressive. Their age averaged just under 65. Half got prostate surgery; the other half were assigned to watchful waiting.

Preliminary results released in 2002 showed only that the surgery cut deaths from prostate cancer. Three more years of follow-up showed a reduction in overall mortality.

Among all men in the study, after 10 years, those getting surgery had a 44 percent lower rate of death from prostate cancer, a 26 percent lower rate of death from all causes, and sharply lower rates of cancer spread.

Brooks said longer-term research is needed to determine how the results apply in this country, where prostate cancer usually is diagnosed at an earlier stage by the PSA blood test; the Scandinavian men mostly were diagnosed when the tumor was large enough to be felt on a rectal exam.