WASHINGTON (AFP) - Surgery appears to be a better treatment option for early prostate cancer than "watchful waiting," particularly for younger patients, according to a Swedish study published Thursday.

In the first clinical trial examining the impact of surgically removing the prostate gland, the team followed 347 randomly chosen patients for the procedure, and closely watched 348 others, according to the study in the New England Journal of Medicine.

The assessment of the nearly 700 men, who averaged 65 years when diagnosed, found that after 15 years, 48 percent of the men in the surgical group died, compared with 58 percent in the closely watched group.

For the surgical group, 16 percent died of the prostate cancer, compared to 23 percent for those being watched.

The risk of cancer spreading "beyond the prostate gland was 12 percent lower for those who received surgery."

The study found that the younger men in the study, those aged around 65 -- benefited most from surgery, while going under the knife presented fewer benefits for older patients.

"Not everybody benefits from surgery, so individual risks and potential gains have to be assessed on the basis of age, other illnesses, tumor type and patient preferences," cautioned Anna Bill-Axelson, chief physician at the Department of Surgical Sciences at Sweden's Uppsala University.

Surgical patients whose tumours grew beyond the prostate gland also ran a "seven-times-greater risk of mortality" due to prostate cancer than those whose tumors were limited to the gland, also warned the report.