Identical Outcomes With RT or Surgery In Early Prostate Cancer

LOS ANGELES--"Prostate cancer is a disease of options,"Douglas Keyser, MD, said at the American Society for TherapeuticRadiology and Oncology (ASTRO) meeting. And individual treatmentdecisions are difficult to make because of the lack of randomizedstudies and head-to-head comparisons between radiation therapyand surgery.

Now, new data from the Departments of Radiation Oncology and Urology,at the Cleveland Clinic Foundation, show that in early prostatecancer, results with radiation therapy and surgery are nearlyidentical, Dr. Keyser said at a scientific session on genitourinarycancer.

The investigators reviewed charts from 1,467 consecutive prostatecancer patients treated between 1987 and 1996 at the ClevelandClinic, looking for those with early prostate cancer (pretreatmentPSAs of 10 ng/mL or less and clinical stage T1 or T2 disease)who had received either radiation therapy or surgery with no adjuvantor neoadjuvant therapy.

Of the resulting 607 patients, 253 had been treated with radiationtherapy and 354 with radical prostatectomy (one third of whomhad positive surgical margins). "The radiation patients weresignificantly older, but overall the pretreatment characteristicsof the two groups were very similar," Dr. Keyser said.

The study endpoint was biochemical relapse-free survival, whichwas defined as a rise in PSA above 0.2 after prostatectomy, anda rise of greater than 1.0 from the nadir after radiation therapy.The data were also analyzed using a newer definition of biochemicalfailure--three consecutive rising PSA levels above the nadir.

"Overall biochemical relapse-free survival was very goodfor the entire group (75% at 5 years) as we would expect for thesepatients," Dr. Keyser said. And the 5-year results were thesame for radiotherapy (75%) and prostatectomy (76%). These resultsdid not vary in the reanalysis based on the newer definition ofbiochemical failure.

An analysis of outcome based on pretreatment factors showed thatpatients with Gleason scores of 7 or greater "seemed to farebetter with radiation therapy, perhaps due to the higher margin-positiverate in these patients," he noted.

Dr. Keyser said that his urology colleagues have pointed out thatdifferences in margin-positive rates can possibly affect outcome."So we did a subset analysis comparing outcomes based onmargin status with radiation therapy outcomes," he said,"and found that even in those patients with negative margins,there was no statistical difference in outcome, compared withthose treated with radiation therapy."

A urologist in the audience questioned the limited follow-up inthe study (median, 24 months). He pointed out that failure afterprostatectomy tends to occur in the first couple of years, whereasfailure after radiation tends to show up at around 3 years, sothat a couple of more years of follow-up are needed before definiteconclusions can be drawn.

Dr. Keyser responded that "so far, the slope of the curvesis not changed when we look at the patients with longer follow-up,but obviously longer follow-up is needed for the entire group."

In both treatment groups, pretreatment PSA level was a significantpredictor of biochemical failure. "Those with PSAs in the4 or less range do very well regardless of treatment," Dr.Keyser said, "but patients with PSAs of 4 to 10 experiencea 30% to 40% biochemical failure rate, and new approaches areneeded to improve these numbers."

Dr. Keyser's colleagues in the study were Dr. Patrick Kupelianfrom the Department of Radiation Oncology and Drs. Craig Zippeand Eric Klein from the Department of Urology.