PHOENIXA matched-pair analysis suggests that early postoperative adjuvant radiation therapy significantly re-duces the risk of biochemical failure in prostate cancer patients with capsular penetration after prostatectomy.
The Thomas Jefferson University researchers identified 149 patients at the Kimmel Cancer Center who had capsular penetration and absence of nodal metastasis after prostatectomy. None of these patients had elevated postoperative PSA within 6 months of the time of radical prostatectomy. They received no prior hormonal therapy or chemotherapy, Richard K. Valicenti, MD, said at the annual meeting of the American Society of Therapeutic Radiology and Oncology (ASTRO).
From this group, the researchers matched 36 patients who received adjuvant radiation therapy and 36 patients who did not receive adjuvant therapy for preoperative PSA, Gleason score, surgical margin status, and seminal vesicle invasion. These are prognostic factors highly predictive of biochemical failure and outcome, Dr. Valicenti said.
With a median follow-up of 41 months (minimum, 2 years), the study showed 17 biochemical failures among the patients who did not receive adjuvant radiation therapy, compared with only four such failures in the adjuvant therapy group.
There was 93% biochemical control in the patients who received adjuvant irradiation vs 66% in patients who were observed, Dr. Valicenti said. This represents an 83% reduction in biochemical failure among patients who had adjuvant treatment.
He added that the study has shown no difference in clinical outcomes (local control, disease-specific survival, or overall survival). I think the lack of a survival difference is due more to the absence of clinical events rather than their presence, he said.