I have in my notes that statistically the ones who do the best are the men who see their PSA decline to less than 0.1 within 9 months from the end of SRT. I can't find my source on that, however, so I could be wrong. I thought it was Stephenson who showed that, but looking at his 2004 and 2007 articles on salvage, I can't find that fact. I do know that it is normal for PSA to be greater than or equal to 0.1 for several months after SRT, even in men who will have durable responses.
Catalona and colleagues found that at 10 years, overall, only 25% of patients were free from PSA progression. However, those who were responders (saw their PSA drop to an undetectable level) did better. 35% of those men were free from PSA progression. Source: www.ncbi.nlm.nih.gov/pubmed/16145393?dopt=Abstract
I think you have to be followed for a long, long time to truly be able to say it worked and you're cured. The curve is still there 6 years after end of treatment, and men are still falling off that curve. Catalona's single-center study going out 10 years is the longest study I know of. I think if I make it to 10 years with no progression, I will be almost sure I'm cured. If I make it to 6 years, I'll be cautiously optimistic. Right now, speaking for myself, I am in a wait and see mode
3 month testing after SRT is normal. At least, that's what I had. After a while, as my PSA was less than 0.1, we switched to 6 month checkups. That's where I am now, just over 3 years out.
Dx Feb 2006, PSA 9 @age 43
RRP Apr 2006 - Gleason 3+4, T2c, NX MX, pos margins
PSA 5/06 <0.1, 8/06 0.2, 12/06 0.6, 1/07 0.7.
Salvage radiation (IMRT) total dose 70.2 Gy, Jan-Mar 2007@ age 44
PSA 6/07 0.1, 9/07 and thereafter <0.1