LONDON — Men with early prostate cancer who choose to closely monitor their disease are just as likely to survive at least 10 years as those who have surgery or radiation, finds a major study that directly tested and compared these options.

Survival from prostate cancer was so high – 99 percent, regardless of which approach men had – that the results call into question not only what treatment is best but also whether any treatment at all is needed for early-stage cases. And that in turn adds to concern about screening with prostate specific antigen blood tests because screening is worthwhile only if finding cancer earlier saves lives.

“There’s been no hard evidence that treating early disease makes a difference,” said Dr. Freddie Hamdy of the University of Oxford, the study’s leader.

The study involved more than 82,000 men in the United Kingdom, ages 50 to 69, who had tests for PSA.