A surgeon performs a robotic prostate operation. Men increasingly have treatment options if their prostate cancer is found at an early stage.

The biopsy shows cancer, so you have to act fast, right? Not necessarily, if it’s a prostate tumor.

Men increasingly have choices if their cancer is found at an early stage, as most cases in the U.S. are. They can treat it right away or monitor with periodic tests and treat later if it worsens or causes symptoms.

Now, long-term results are in from one of the few studies comparing these options in men with tumors confined to the prostate. After 20 years, death rates were roughly similar for those who had immediate surgery and those initially assigned to monitoring, and surgery had more side effects.

“Many men, when they hear the word cancer, you want to do something about it,” said one study leader, Dr. Gerald Andriole, urology chief at Washington University in St. Louis. “The reality is, if you have a low-risk cancer, like the study shows, you don’t need treatment, certainly not urgently.”

It’s not all black and white, though. Early stage doesn’t necessarily mean low risk. Some results in the study lean in favor of surgery, and it does have some advantages. It also may improve survival for certain groups. Here’s what this and other studies tell us about who does and doesn’t benefit from surgery.

WHY NOT TREAT?

Start with a fact many find hard to accept: Not all cancers are destined to kill. Some prostate tumors are deadly, but most grow so slowly that men will die of something else.

Treatments — surgery, radiation or hormone therapy — can cause impotence, incontinence, infections and other problems, and sometimes do more harm than the disease ever would.

Monitoring doesn’t mean do nothing. Men can get frequent tests, and there are more and better ways to detect disease progression now than there used to be, so there’s usually still a chance to treat and potentially cure it if it starts to worsen, Andriole said.

THE EVIDENCE SAYS

Only a few studies have tested monitoring versus immediate treatment. One found no difference in death rates after more than 20 years; another found surgery improved survival odds, but only for men under 65.

Those were done before wide use of PSA blood tests, back when more tumors were found because they caused symptoms, which often means more advanced disease.

Researchers wondered: Would the results be the same with modern screening and treatments?

The new study, sponsored by the U.S. Department of Veterans Affairs, aimed to answer that. Doctors assigned 731 men to observation or surgery. After a decade, survival rates were similar, but doctors wanted longer follow-up.

Now, after 20 years, two thirds of these men have died and the original conclusions still stand, though the numbers leaned in surgery’s favor.

Fewer men died in the surgery group, but the difference was small enough that it could have been due to chance. Only about 9 percent of men ultimately died from prostate cancer, showing how relatively seldom the disease proves fatal.