Researchers believe the "genetic signature" test will help doctors determine which patients need extra help after initial treatment.
"Men who fail treatment within two years may be at the highest risk of dying from their prostate cancer," said lead scientist Professor Robert Bristow, senior scientist at Ontario Cancer Institute (OCI).
"Existing methods for identifying high risk patients are imperfect, so new tests are required that are better at predicting which patients will have their cancer recur. These men can then be offered additional treatments, such as chemo and hormone therapy, that will combat the prostate cancer throughout their entire body, rather than therapies solely focused on the prostate, in order to improve their chances of survival.
"This is the first report of a test using information derived from biopsy samples that can predict with close to 80% accuracy which men are at high or low risk of their prostate cancer recurring."
The scientists analysed biopsy tissue samples taken from 126 treated men with prostate cancer who were thought to be at intermediate risk of their cancer returning.
They looked at each patient's whole genetic code, or genome, searching for missing, extra, or irregular sections of DNA.
From this information they were able to identify signature patterns linked to a high or low risk of recurring cancer. The test was used to predict outcomes for a second group of 150 patients who had their prostate tumours removed by surgery.
A secondary study by the same team found that tumours affected by hypoxia - starved of oxygen -were most associated with worse survival.
"Importantly, we found that when we combined the signature with the additional information about the tumour's oxygen content, this made the genetic test even more accurate," said Prof Bristow, who presented the results at ESTRO33, the 33rd meeting of the European Society for Radiotherapy and Oncology in Vienna, Austria.