Barry is right. But to be specific with RT you may have it as a primary treatment or as a follow up treatment as I did after I had a radical prostectomy .
In this case it may be given before any recurrance of PCa. This is known as adjuvant RT. When the RT is given after a recurrence of PCA it is called salvage RT.
It is not a standard treatment path in this country. There is a trial taking place to determine if RP should be followed by other treatments ie RT and/or HT in high risk cases
Bri