Level 1 evidence has to apply to your patient group. This is where the controversy lies. In the SWOG 8794 adjuvant vs. salvage study, the median PSA at time of salvage was 1.0. We know from other data (
http://forums.studentdoctor.net/showpost.php?p=14372354&postcount=7) that the salvage rate depends on the PSA at the time of salvage. With frequent PSA and "ultra-sensitive" tests, patients should be getting treated now at about the 0.2-0.5 level based on ASTRO/AUA consensus guidelines.
So the question becomes: does SWOG 8794 apply to modern practice? i.e. the patients who were "salvaged" with a PSA >0.5 were likely setup to fail, where they don't necessarily need to be. We have to ignore some other factors that would push you to treat immediately, such as patient compliance or urologists not doing the right thing in your community. Knowing that PSA <0.5 is much more salvageable, will randomization of patients to salvage ONLY if the PSA is <0.5 vs. adjuvant for high risk factors (SVI, T3b, positive margin) make a difference in survival?
There is evidence for equivalence of adjuvant and salvage radiation only when salvage is performed in a timely fashion:
http://www.sciencedirect.com/science/article/pii/S009042959900299X. This also may be a reason why the SWOG found a survival and distant metastasis free benefit, while the German and EORTC studies did not. Also, the EORTC only found a benefit for positive margins on subset analysis (
http://jco.ascopubs.org/content/25/27/4178.long) which could be the most important factor. Though I don't know what the median PSA at time of salvage were for those studies.
So in the end, it's still reasonable to only give adjuvant radiation for positive margins, or to be dogmatic about the SWOG study and recommend adjuvant radiation for all high risk features until more trial data becomes available.