Did you set out to conduct such a long study, or did it just evolve into what it became?

Dr. Critz:  In the early 1980s when I was developing our program of seed implantation followed by external beam radiation, the motivation to follow patients and study their subsequent course was simply to see if this program worked: to study men’s disease-free status and complications of treatment to see if we could make improvements in treatment technique.

Initially, all follow-up was for internal use simply to improve our program. Later, when we perceived the magnitude of our database, especially with the development of the PSA test for clinical use in 1987, I began to think about publications, with the first peer-reviewed study published in 1995. The long follow-up in this 25-year report was simply an evolution of these original ideas.

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At the 25-year mark, median follow-up was 11 years. What was the average age of your study patients at enrollment?

Dr. Critz:  At the time of seed implantation, the average age of men was 65 years. This is an interesting point for, as I recall, men in the United States live an average 77 years. Thus, it requires a large sample size to find enough men who live into their late 80s and 90s to be evaluated for a 25-year study.

Will you publish findings at 30-year follow-up and beyond? Or does the relatively late age of diagnosis for this disease diminish the usefulness, or even the possibility, of data collected after that point?

Dr. Critz: Our study is ongoing, but whether there will be any value to analyzing men after 25-year follow-up may be questionable. The reason we continue to analyze our men is to add to the sample size at 15-, 20-, and 25-year follow-up.

Is there a point at which follow-up data no longer contribute to the scientific knowledge on this subject?

Dr. Critz: Due to the small sample size at 20-year follow-up (30 men) and 25-year follow-up (five men), I do not think one can make a definitive statement about length of follow-up except to say that it should continue indefinitely for the present time until we get more information.

For example, when I wrote the paper, the longest time to recurrence was at 15.5-year follow-up. Subsequent to writing the paper, we have had four more recurrences, with the longest time to recurrence now being 17 years.

Were you surprised by the finding that radiation was equal to radical prostatectomy in terms of the risk of late recurrence?

Dr. Critz: Yes, I was surprised to find that our late recurrence rate, defined as recurrence after 10-year follow-up, of 5% was essentially the same as the 6.4% following radical prostatectomy at Johns Hopkins. I believe the similarity is, again, based on using the same definition of recurrence.

What has been the reaction of the urology community toward these findings?

Dr. Critz: The response to the report has been overwhelmingly positive both from urologists in academic settings and those in private practice. In fact, I have not heard any negative comments. I think urologists respect the findings from our program because we stress that there should be a universal PSA definition of recurrence following either radiation or radical prostatectomy for prostate cancer and not the current status of a radiation definition separate from a surgical definition.

Were there any notable study limitations that urologists should take into account when interpreting the results?

Dr. Critz:  The only notable study limitation of this report concerns the small sample size at 20-year follow-up and 25-year follow-up, which, as noted earlier, is why we have an ongoing research program to address this issue. Achievement of follow-up beyond 10 years and especially beyond 15 years is difficult because of the simple fact that men die of other causes, develop severe comorbidity such as Alzheimer’s, and just get tired of having the yearly PSA test.

Have your findings changed the way you advise men seeking treatment for prostate cancer?

Dr. Critz:  Since I have continually monitored the disease-free-survival results of our program, which have always been calculated with the surgical definition of recurrence, I was not surprised by the findings and, thus, our paper has had no real impact on how we advise men seeking treatment for prostate cancer. Due to the 5% of recurrences occurring after 10-year follow-up, I have stressed that men continue follow-up indefinitely. This is especially important when we treat young men who have a projected life span of 20 to 30 years.

Do you think your findings might change how men in general are advised regarding prostate cancer treatment?

Dr.Critz: The major way this report might affect how men are advised regarding prostate cancer treatment is to suggest to men that when speaking with physicians they should not ask about “cure rates” but more precisely ask what their chance is of having a PSA level below 0.2 ng/mL 10 to 15 years after treatment.

Are you conducting any other research in this area?

Dr. Critz: The areas of particular interest that we are evaluating are the importance of post-treatment PSA nadir and the importance of biopsy perineural invasion, and to expand upon our findings of late recurrence.