Probability of remaining recurrence-free after salvage radiation

In 2007, Stephenson et al. published a nomogram that predicted the probability of success of salvage radiation after post-prostatectomy biochemical failure. Biochemical failure was defined as a PSA≥0.2 ng/ml. Memorial Sloan Kettering Cancer Center has made the nomogram publicly available at this link. But that data was put together before ultrasensitive PSA tests became widely available, and before three randomized clinical trials demonstrated an advantage to adjuvant radiation over waiting. Several studies now suggest (see this link) that early salvage may provide the same benefit as adjuvant radiation therapy, but with less risk of overtreatment.

Tendulkar et al. have now updated the Stephenson nomogram. I posted a version at the following link:

pcnrv.blogspot.com/2016/08/probability-of-remaining-recurrence.html

Gemlin-

This nomogram gives no information about 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:

Tendulkar said...
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.

- Allen

lifeguy,

The new nomogram shows the freedom from recurrence at 5 and 10 years. My example only showed the ten year numbers. It sounds like you were looking at the old one.

It can be very helpful when your odds are very good or very bad. Less helpful in the middle.

- Allen

Allen -

Well, I double checked other sources and getting points for negative surgical margins is not a typo.

Not sure why that is? What is the logic?

Bobby Mac

Octorobo-

That could be a valid reason --

Bobby Mac

Thanks for the timely article, TA, as I just completed SRT myself.

I plugged my numbers into the nomogram:

- ADT: No (49 points)
- Gleason Score: 6 (0 points)
- Extraprostatic Extension: Yes (My pathology actually indicated that EPE could not be determined, so I answered yes, 22 points)
- Surgical Margins: Positive (0 points)
- Seminal Vesicle Invasion: Yes (24 points)
- Pre-RT PSA: .07 (5 points)
- Radiation Dose: ≥66 Gy (0 points)

Total Points: 100

Based on the nomogram, I have a 70% probability of remaining BCR-free for the next 10 years. I sure hope that proves to be true.

Regarding the points given for surgical margins, I believe the lower point value given to a positive margin is because with a positive margin the cancer is assumed to be localized to the prostate bed, giving the SRT a better chance of eradicating it, thereby improving your chances of remaining BCR-free. With no positive margin, the chances of the cancer being localized to the prostate bed is less, therefore reducing the chances the SRT will hit it.

A missing risk factor in the nomogram might be "time from surgery" until "PSA rise". Longer time (> 2 years) means (I think) less risk for mets and then higher probability for SRT success since only local recurrence. So fast PSA rise should give points, or ...?

Another thing, with Johns G6, which never give mets, you would assume more than 70% probability of remaining BCR-free. Why only 70%?

George -

I put my numbers into the salvage radiation MKCC nomogram and it calculation a 6 year progression free of 39% after SRT.

I then substituted my positive margins, which they are, to not being positive and the progression free dropped to 24%.

That does square with the Stephenson nomogram.

Bobby Mac

Post Edited (Bobby Mac) : 8/26/2016 11:19:50 AM (GMT-6)

Allen -

Yes, I see the logic -

Bobby Mac