ANAHEIM, CaliforniaAfter prostatectomy, early adjuvant radiation therapy for margin-positive disease appears to significantly decrease the rate of biochemical failure, according to a report from the American Urological Association annual meeting (abstract 684).
The study from the Lahey Clinic, Burlington, Massachusetts, showed that in properly selected patients, the initiation of radiation therapy within 6 months of surgery reduced the likelihood of cancer recurrence by two thirds. Patients who received early radiation therapy had a 12% recurrence rate vs 38% for patients not receiving early irradiation (P < .0001), reported Samuel Shuffler, MD, a senior resident at the Lahey Clinic.
"The use of radiation within 6 months of a prostatectomy in which the disease has spread beyond the prostate capsule can make an enormous difference in the recurrence of the disease," commented principal investigator John A. Libertino, MD, chair, Department of Urology.
The study included 296 patients with pathologic T3 disease, chosen from a retrospective analysis of 1,175 patients treated between 1988 and 2000 with radical prostatectomy. Of the 296 patients, 66 received early adjuvant radiation therapy, and the remaining patients received hormonal or delayed radiation therapy at the time of disease recurrence.
Preoperative PSA levels were 13.9 ng/mL for the adjuvant therapy group and 10.4 ng/mL for patients not receiving radiation therapy. The median pathologic Gleason score was 7 for both the 296-patient subset and the entire study population.
The adjuvant therapy was in the form of high-energy (10 to 15 mV) four-field conformal radiation. "The addition of radiation did not increase the incontinence rate, nor did it have other major side effects," added co-investigator Theodore C. Los, MD, a radiation oncologist at the Lahey Clinic.
Dr. Shuffler cautioned that this was a small, retrospective, nonrandomized study of early radiation therapy. "But it suggests that untreated positive margins resulted in an increase in biochemical progression," he said. "Early radiation therapy significantly reduced the risk of biochemical failure."