PURPOSE: To compare disease-free survival (DFS) rates using a >0.4 ng/mL biochemical failure definition with the Phoenix (nadir+2 ng/mL) failure definition by analyzing a consecutive cohort of 1006 patients treated with low-dose-rate prostate brachytherapy (LDR-PB) monotherapy.
METHODS AND MATERIALS: Data for first 1006 consecutive LDR-PB implants (1998-2003) were extracted from a prospective database. Patients had low- (58%) or intermediate (42%)-risk disease. Three months neoadjuvant and 3 months concomitant androgen deprivation therapy were used in 65% of cases. The Phoenix definition was modified to "unfail" patients who had a benign prostate-specific antigen (PSA) bounce.
RESULTS: The median followup is 7.5 years. The median PSA at latest followup for disease-free patients was 0.04 ng/mL. The Phoenix definition yielded 5- and 10-year Kaplan-Meier DFS estimates of 96.5 ± 1.2% and 93.7 ± 2.0%, respectively. Applying the >0.4 ng/mL threshold reduced these estimates to 94.4 ± 1.6% and 88.8 ± 3.0% (log rank, p = 0.015).
CONCLUSIONS: Compared with Phoenix, applying a >0.4 ng/mL failure definition increased biochemical failure by ∼2% at 5 years and ∼5% at 10 years. These data show that Phoenix did not greatly exaggerate DFS estimates compared with a surgical-type threshold. However, this observation is a consequence of the exceptionally low residual PSA values characteristic of LDR-PB and cannot be generalized to other forms of radiation therapy.
Written by:
Morris WJ, Pickles T, Keyes M, McKenzie M, Spadinger I. Are you the author?
Division of Surgery, Department of Radiation Oncology, Faculty of Medicine, University of British Columbia, British Columbia, Canada; Department of Radiation Oncology, Vancouver Cancer Centre, 600 West 10 Avenue, Vancouver, British Columbia, Canada V5Z 4E6.
Reference: Brachytherapy. 2013 Aug 14. pii: S1538-4721(13)00301-2.
doi: 10.1016/j.brachy.2013.06.006
PubMed Abstract
PMID: 23953812
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