I asked about Space OAR with my RO for my upcoming treatments, after hearing about it from a relative who recently underwent radiation therapy for his PC problem and used it. I was told that my provider (Kaiser in Northern CA) does not use Space OAR any longer because of the relatively high rate of problems with it. Reading the comments here, I can see that they have a valid argument and I'll probably be better off without it. Even though it may increase the risk of other problems may be increased without it.

Guess I'll know more in a few weeks, when my external treatment starts. Having brachytherapy on Tuesday to start the process before the external photon radiation starts.