when to do post surgery SRT

I think 0.2 has been the traditional point where most doctors would declare a recurrence, but there is no universal standard.

Dr. Andrew Stephenson and other researchers have identified 0.5 or lower as a "best" point to start SRT.

According to Stephenson (et al): "An estimated 48% of patients who received SRT alone at PSA levels of 0.50 ng/mL or less were free of progression at 6 years, compared with 26% for those treated at higher PSA levels."
Source: Journal of Clinical Oncology, Vol 25, No 15 (May 20), 2007: pp. 2035-2041
Predicting the Outcome of Salvage Radiation Therapy for Recurrent Prostate Cancer After Radical Prostatectomy
Andrew J. Stephenson, Peter T. Scardino, Michael W. Kattan, Thomas M. Pisansky, Kevin M. Slawin, Eric A. Klein, Mitchell S. Anscher, Jeff M. Michalski, Howard M. Sandler, Daniel W. Lin, Jeffrey D. Forman, Michael J. Zelefsky, Larry L. Kestin, Claus G. Roehrborn, Charles N. Catton, Theodore L. DeWeese, Stanley L. Liauw, Richard K. Valicenti, Deborah A. Kuban, Alan Pollack
Full text: http://jco.ascopubs.org/cgi/content/full/25/15/2035

I think you're right. Your hypothetical numbers would be fine, *except for the trend*. A clear upward trend over time is enough for many patients and their doctors to start a secondary treatment before PSA reaches the 0.2 threshold. I think there are some on this board who started around 0.1.

In my case, I was being monitored with the standard, non-ultrasensitive test. My was less than 0.1 at 90 days after surgery, then 0.2 at 6 months (at which point my uro SHOULD have rung the bell and referred me to oncologists, or at least have retested fairly soon, but he didn't) then 0.6 at 9 months. At that point, I scrambled to get going with SRT as quickly as possible, consulting with both a radiation oncologist and medical oncologist. By the time I started SRT, I was at 0.7.

From Mel: Say my PSA scores were .01, .02, .03, .04. These numbers look great when compared to 0.2. So, is this zero club numbers? It seems to me we have a short doubling time here.

Mel, the difference between .01 and .04 or .05 is so minute that many doctors won't even pay attention to it. PSA, like your weight, will fluctuate from day to day. When your post-surgery PSA hits 0.1 or higher, then its time to pay attention. Generally, any PSA reading that starts with 0.0 is considered undetectable and earns you membership in the zero club.

Hope your recuperation is proceeding smoothly.

Let's try a thought experiment. Suppose that your lab is unable to reliably determine such low PSA values. Let's imagine that they "fake" it by having a hat with four balls numbered .01, .02, .03, .04. To give your test results they just reach into the bag, pull out a ball, and report that number. Thus the chances of any particular sequence of four numbers on four sequential tests is 1/4 * 1/4 * 1/4 * 1/4 = 0.004. Unfortunately that makes .01, .02, .03, .04 a pretty rare event although one should also remember that .01, .01, .01, .01 is equally rare.