Hi Clarabella, firstly welcome to this site and I am sure you will get some helpful information on here.
I think you will need to give as much information about your dads diagnosis, for example what was his PSA reading in 2011 and was he given a Gleason score and a staging? Any further info during treatment will enable someone to answer you I am sure.
I personally have no experience of the treatment that your dad is having and my answering will bump your post back to the top.
Best wishes to you and your dad
Regards Chris/Woody
Life seems different upside down, take another viewpoint