For those who have undergone SRT, how many GY did they use?
When I try the MSK nomograph
for SRT, I get interesting results.
My numbers are: 4.19 PSA
Surg. margins positive'
Pre-radiotherapy PSA 0.21 (estimate)
PSA doubling time: 3 months
Months disease free: 13
I get a 36% roughly probability of 6 -year progression free survival
If I change the GY to 66, it goes up to 52%!!!
If I lower it, it then goes down.
If I go to 72, then the prob. is 45%.
Isn't that very strange? I thought the higher the GY was, the better chance you had (with more SE).
So, what is the standard GY dose for SRT?