Some may find it surprising that Frank A. Critz, MD—a radiation oncologist who focuses on prostate cancer—generally considers radical prostatectomy to be the go-to treatment for localized disease.

But now that he and fellow investigators have completed a 25-year study showing radiation therapy outcomes to be equal to those of radical prostatectomy under the strict surgical definition of prostate cancer control (The Journal of Urology 2013;189[3]: 878-883), Dr. Critz—the founder and medical director of Radiotherapy Clinics of Georgia–Decatur (an affiliate of Vantage Oncology), can comfortably recommend both options to patients.

Other than the impressively long follow-up period, what sets your findings apart?

Dr. Critz:   An equally important factor in our report is how the 25-year disease-free-survival rates were calculated. They were calculated with the surgical definition of recurrence following radical prostatectomy instead of the universally used ASTRO [American Society for Radiation Oncology] or Phoenix definition of recurrence used by radiation oncologists when calculating disease-free-survival rates. Use of the surgical definition of recurrence was placed in the title of this study since this factor is so important.

The surgical definition of recurrence is based upon a PSA rise above 0.2 ng/mL or a nadir above this level. In contrast, neither of the radiation oncology definitions of recurrence requires any specific PSA level.

Thus, the radiation definitions have completely different meanings relative to the surgical definition of recurrence. From a practical standpoint, as documented both after radical prostatectomy and after irradiation, calculation with the two radiation definitions significantly inflates disease-free-survival rates relative to calculations using the surgical definition of recurrence.

When radiation oncologists write research papers comparing irradiation and surgical disease freedom, the effect of the definition of disease freedom on calculations is virtually always ignored.

In fact, this is the only radiotherapy publication on disease-free-survival rates for prostate cancer that compares PSA-defined disease-free-survival rates of surgery with irradiation using the same definition of recurrence—the surgical definition.

Why is this so important?

Dr. Critz: Although I am a radiation oncologist with a special interest in prostate cancer, I firmly believe that, in general, the gold standard for treatment of localized prostate cancer is radical prostatectomy. Nonetheless, when I consult with men newly diagnosed with this disease, I inform them that they have a choice between our radiation program and radical prostatectomy since the cure rates are the same.

I maintain my professional integrity in making this recommendation because I know, as documented by our 25-year disease-free-survival-rate research paper, that at 15-year follow-up, the results of our program are at least equal to those of radical prostatectomy at Johns Hopkins and Memorial Sloan-Kettering when calculated with the same definition of recurrence.

On the other hand, I believe if I inflated our results by calculating with either of the radiation definitions and made similar comparisons to radical prostatectomy, I would be providing misleading information to men who trust their health care to me.

To put it in plain language, if we as radiation oncologists are going to advocate a particular radiation program in lieu of surgery, we should make an apples-to-apples comparison and not apples-to-oranges as is universally done.

Another important point is the fact that we analyzed men treated from 1984 to 2000 to correspond to the same time period of the radical prostatectomy publications with which we make comparisons. This is an important point because the management of prostate cancer has greatly changed with time.

The most important development over this time span was the use of the PSA test for screening and, thus, earlier detection of prostate cancer. Again, just as with the definition of recurrence, comparison of men from the same time period is often overlooked when comparing results of surgery and radiation.

Your study began with 3,546 hormone-naïve men treated with a retropubic or, later, transperineal prostate seed implantation followed by external beam radiation. Was the study conducted by the same group of investigators, start to finish?

Dr. Critz: The same group of investigators who treated the patients followed them over the 25 years analyzed for this report. I performed all the retropubic seed implants and other physicians began performing seed implants when we changed to the ultrasound technique in the early 1990s. Thus, all the patients in the study have been followed by physicians along with our database staff.