I'm guessing the number one concern for patients with low-risk cases who are considering Active Surveillance (AS) is whether they are putting themselves at increased risk should AS monitoring prove that they need treatment at a later date.
Fortunately, evidence is accumulating that that risk is non-existent or minimal. At least one such study has been published based on the AS program at Johns Hopkins, but a new study has just been published based on results in California. It was mainly done at the U. of California, Davis, but PR
Carroll is the senior (last) author, and I believe that is Dr. Peter Carroll, the eminent urologist, Chief of Urology at the U. of California, San Francisco, and leader of a major AS program at UCSF. That may mean that UCSF AS program data, and perhaps other data in the U. of California system, may have been used in the study.
Here is the study citation:
BJU Int. 2010 Aug 26. [Epub ahead of print]
Surgical management after active surveillance for low-risk prostate cancer: pathological outcomes compared with men undergoing immediate treatment.
Dall'era MA, Cowan JE, Simko J, Shinohara K, Davies B, Konety BR, Meng MV, Perez N, Greene K, Carroll PR
Department of Urology, University of California, Davis, CA, USA.
After looking at whether there was a greater tendency toward an increase in Gleason score from biopsy to surgery sample, an increase in stage, or an increase in the likelihood of positive surgical margins, the authors reached this conclusion:
"... The present analysis did not show an association between RP after a period of AS and adverse pathological features for men with low-risk disease."
In other words, deferring therapy did not appear to increase risk of a poorer surgery outcome. However, the study was quite small, involving only 33 men in the AS + RP group (but 278 men having an RP within 6 months of diagnosis in the other group. The small size means that the conclusions are not presented with a high degree of statistical confidence. I'm thinking it may be hard to find men who have been on AS for longer than six months who then go on to have an RP; that's because, as published research indicates, a high percentage (around 70%) of men who start AS do very well on the program, not needing a definitive therapy over a long term or ever.
I believe that the Toronto AS program has also published on this issue, but I don't have the information ready at hand. Other major AS groups I'm aware of are at Memorial Sloan Kettering, the Erasmus Medical Center, and MD Anderson.