This nomogram gives no
whether any of those risk factors indicate the need
for salvage radiation, it only tells one how likely the salvage radiation is to be successful, given those risk factors. As you can read for yourself, only a minority (18%) of patients had a uPSA available and only 18 patients out of 2,460 patients had a uPSA under 0.05 ng/ml when treated. So this study wasn't powered to detect the effect of very low PSAs. Yet, even with this small sample, lower PSA had a statistically significant effect on the success of salvage radiation. In fact, the hazard ratio almost doubled (1.88) for every increase in PSA ng/ml.
It should come as no surprise that men with fewer risk factors have more successful SRT. However, success of SRT does not mean that SRT was needed in the first place. For information as to whether someone needs
salvage radiation in the first place, we rely on randomized clinical trials and other analyses. This only tells us that men treated at lower PSAs had better outcomes. What the authors say is:
Patients across all Gleason Score subgroups had significantly better outcomes with initiation of early SRT at lower PSA levels, supporting data from the SWOG randomized trial, which included patients with adverse pathologic features such as EPE, SVI, or positive surgical margins.Those with lower-grade prostate cancer had more favorable freedom-from-biochemical-failure outcomes and lower DM rates compared with patients with higher-grade disease, although outcomes were still worse when SRT was initiated at higher PSA levels.
The authors conclude "Early SRT at low PSA levels after RP is associated with improved freedom from biochemical failure and distant metastasis rates. "
This represents the consensus opinion of the 10 institutions, including Cleveland Clinic, Mass General, Mayo Clinic, Washington U., Duke, UMich, UChicago, etc. Other institutions, including MSKCC, UCLA, and Fox Chase, also agree.