New research strongly reinforces the notion that prostate cancer is vastly overtreated with often dire results.

A study out Wednesday in the New England Journal of Medicine focused on treatment side effects, following a group of 3,533 men for 15 years after they got either surgery (called prostatectomy) or radiation for cancer that had not spread beyond the prostate. Radiation produced fewer side effects — especially in the first years after treatments– but both groups experienced huge impacts.

“This paper tells you that if you get treatment there are a lot of side effects regardless of the therapy you chose,” the senior author Dr. David Penson, professor of urologic surgery at Vanderbilt University Medical Center, said in an interview.

Most men were in their sixties when they were first treated. Two years after treatment 60.8 percent of the men who had undergone radiation had erectile dysfunction, compared to 78.8 percent of those who chose surgery. By 15 years, the numbers became 87 percent and 93.9 percent. Many men also suffered urinary and bowel problems and those, too, grew worse with time.

A rational argument is that such side effects are acceptable if the treatment is saving lives. But the paper raises serious doubts.

“So many of these men have low-risk disease that probably doesn’t need to be treated,” Penson said.

Men typically undergo needle biopsies because they have elevated levels of the blood test called prostate-specific antigen (PSA). If the needle finds cancer cells, a pathologist measures their severity, resulting in what is called a combined Gleason score that ranges from 1– the least severe– to 10.

Most prostate cancers score between 6-7. Several top urologists at university medical centers agreed that prostate cancer below a score of 6 should be watched, but not treated. Yet in this latest study, which is a reliable cross-section of how medicine is actually practiced, about 60 percent of the men who underwent treatment had scores of 2 to 4.

The findings prove that “a staggering percentage of men with totally inconsequential prostate cancer got treated and suffered the consequences,” says oncologist Dr. Marc Granick of Beth Israel Deaconess Medical Center and Harvard Medical School, who was not involved the study.

Undoubtedly, prostate cancer can be deadly. Estimates are that it will kill almost 30,000 men in the United States this year, second only to lung disease as the major cause of cancer deaths in men. But the problem is, there are at least two kinds of prostate cancer.

The common form appears in the majority of men over age 50, grows slowly, and never presents a health threat. The other form spreads rapidly and can lead to a horribly painful death, usually from malignant cells invading the bones. Doctors cannot tell the difference between the dangerous and harmless cancers. Researchers are looking for genetic markers that would make the critical distinction, but they have yet to find them.

Meanwhile, increasing numbers of prostate cancer specialists argue that the sensible path is for men with lower combined Gleason scores to undergo active surveillance (formerly called watchful waiting), come back for future tests and forgo treatment until it is indicated. Often they will never need treatment.

That doesn’t happen, however. Penson said recent surveys show that fewer than one in four men who are candidates gets active surveillance. The majority get surgery or radiation.

One reason for the intervention is “incentives for the facility and for the providers” — in other words, money for hospitals and doctors. “Also,” he adds, “patients don’t like to hear ‘I have cancer and I’m just going to watch it.’” But patients should demand and doctors should educate that “just watching it” is perfectly safe in many cases.

Learning that lesson could spare an enormous amount of misery and money.