(Reuters Health) - - In men with localized prostate cancer discovered because they had symptoms or noticed during a work-up for another medical problem, radical prostate surgery leads to an average of three extra years of life compared to a “watchful waiting” approach, researchers say.

The benefit of surgery was most pronounced in men who were under age 65 when their tumor was diagnosed, a new, long-term Scandinavian study found.

The results, published in The New England Journal of Medicine, don’t apply to prostate cancer detected during screening, such as with blood tests to measure prostate specific antigen (PSA).

The study does, however, add new information to help guide treatment of men with symptomatic or “incidentally” discovered prostate cancer.

But the findings are complicated by the fact that treatment options have changed since the study began in the 1990s.

Today, PSA testing often spots prostate tumors much earlier, and patients have the option of so-called active surveillance, or watchful waiting, wherein doctors closely monitor tumors and begin treatment when the cancer seems to be getting aggressive. Typically, prostate tumors grow so slowly that men will likely die from something else before the cancer claims them.

Nonetheless, the results are “important because this is the longest follow-up we have,” said Dr. David Penson, chairman of urology at Vanderbilt University Medical Center in Nashville, who wasn’t involved in the study. “It shows that if I have a long life expectancy and if I have higher-grade disease, I probably need to get some treatment because there’s an advantage to surgery, and it’s not an insignificant advantage.”

“If I’m an older, sicker guy with heart disease and my life expectancy is less, maybe I don’t have to have it treated,” Penson told Reuters Health in a telephone interview. “If I have low-grade disease, maybe I don’t need to be treated at all regardless of how old I am.”

“What we show is that radical prostatectomy can cure prostate cancer but it’s only for those who develop a lethal disease and who are healthy enough to not die from something else,” study leader Dr. Anna Bill-Axelson of Uppsala University in Sweden told Reuters Health by phone.

Most people have low-risk disease, she said.

“Even in our study with advanced tumors, almost 70 percent of the men died from other causes, so it shows you shouldn’t treat immediately, especially low- or intermediate-risk tumors,” she said. “You should wait and see if they get more aggressive and then treat them.”

The trial involved 695 men at 14 centers in Sweden, Finland and Iceland.

During follow-up for an average of 23 years, there were 45 percent fewer prostate cancer-related deaths in men who got radical surgery.

By 2017, 80 percent had died from any cause. Among men who had immediate surgery, 72 percent died; among those who didn’t, 84 percent died.

Prostate cancer accounted for 20 percent of deaths in the surgery group and 31 percent of deaths in the watchful waiting cohort.

All volunteers were under age 75 at the start, with a life expectancy of at least 10 years.

The cancer spread in 27 percent of the surgery group and in 43 percent of the watchful waiting group.

Radical prostatectomy produced the most benefit among men diagnosed before age 65. Among these men, “overall mortality was 15 percentage points lower, mortality due to prostate cancer was 15.1 percentage points lower, and the risk of metastasis was 18.6 percentage points lower in the radical-prostatectomy group than in the watchful-waiting group,” the researchers conclude.

SOURCE: bit.ly/2UrK62J The New England Journal of Medicine, online December 12, 2018.