Most men diagnosed with low-grade prostate cancer may not need radical treatments such as surgery or radiotherapy, which can have serious side effects, British researchers said on Thursday.

A modeling study by scientists at the Institute of Cancer Research in England has shown that men whose cancer is detected early with a screening test are unlikely to die from the illness.

So treatments, such as surgery to remove the prostate gland or radiotherapy, which can cause incontinence and impotence will probably not improve their survival.

“Most men with prostate cancer detected by PSA screening will live out their natural span without the disease causing them any ill effects,” said Dr Chris Parker whose findings are reported in the British Journal of Cancer.

“The decision whether to have radical treatment can be tremendously difficult for the patients,” he added.

The modeling study predicted that the chance a man aged 55-59 with a low-grade cancer dying of the disease within 15 years, even without treatment, is about one in a 100.

But the research suggests that men with high-grade advanced cancer would benefit from treatments such as surgery or radiotherapy.

The PSA test measures levels of a protein called prostate-specific antigen, which is produced by the prostate gland, in the blood. It has enabled doctors to detect the cancer much earlier than they previously could.

Parker and his team are testing a new prostate cancer management technique called Active Surveillance, which aims to target treatment only to men who need it.

“Patients are closely monitored and the choice between radical treatment and continued observation is based on evidence of disease progressions,” he explained.

Prostate is one of the most common cancers in men. Each year 543,000 new cases are reported worldwide. The disease kills 200,000 mostly older men in developed countries, according to the International Agency for Research on Cancer.