With localized prostate cancer the treatments of choice have generally been radioactive beam, radiactive seed or prostatectomy. All are very effective in stopping a low stage cancer. Effectiveness comes with side effects though.
Incontinence and impotency are the most common side effects of all three treatments. There is a newer treatment called high intensity focused ultrasound (HIFU) that has been tested more extensively in the UK. While not yet fully accepted, the first 5 year survival studies are out and the rate is about 80%, with fewer side effects.
These numbers put HIFU on the same plane as radiotherapy from a survival standpoint. HIFU treatment had been on the chopping block, doomed to be relegated to clinical trials only until this study. This will likely push it toward mainstream treatment.
Bottom line. A low stage, low grade prostate cancer, successfully treated will generally lead to better than standard rates as long as the PSA reaches certain threshholds. With radiotherapy, the PSA needs to reach .5 and remain at or below .5 for a year. I would expect the same guidelines will be applied to HIFU.