Radiation can be very effective. The one drawback is that you never really know what your Gleason score was or if there were other issues inside your prostate that weren’t seen in the biopsy. I was a 3+4 after biopsy but a 4+3 after surgery. I’ve run into many people that are 4+5 after surgery.

I had 40 sessions of salvage radiation 12 years ago and The only side effect was incontinence starting six years after the Radiation. I had a prostatectomy before that so that could be the cause too.

I know a lot of people that I had radiation and 10 or 20 years later don’t have problems. One thing though, If you have surgery you can usually have the nerves spared, which can allow you to get an erection after. If you have radiation, they cannot spare the nerves and burn them up. That frequently leads to ED after a few years.

People who have radiation as their primary treatment have been told by doctors that surgery isn’t really an option if there’s a reoccurrence. Other options are not really mentioned..

This study shows that both salvage focal therapy (HIFU and cryotherapy) and salvage surgery were equally effective at extending the life of a patient that started off with radiation.

Those that had focal therapy had fewer perioperative complications.
https://jamanetwork.com/journals/jamaoncology/article-abstract/2844900
Some more information about future issues due to radiation

In a study of about 145,000 men with prostate cancer, the Stanford team found that the rate of developing a later cancer is 0.5% higher for those who received radiation treatment than for those who did not. Among men who received radiation, 3% developed another cancer, while among those who were treated without radiation, 2.5% developed another cancer.
https://med.stanford.edu/news/all-news/2022/070/prostate-radiation-slightly-increases-the-risk-of-developing-ano.html