PURPOSE: To validate the prognostic value of interval to biochemical failure (IBF) in patients with high-risk prostate cancer (HiRPCa) treated with combined-modality radiation therapy (CMRT) with or without androgen deprivation therapy (ADT).
METHODS AND MATERIALS: We conducted a retrospective review of HiRPCa (prostate-specific antigen >20 ng/mL, Gleason score [GS] 8-10, or clinical T stage T3-T4) treated with either dose-escalated external beam radiation therapy (EBRT) or CMRT. Interval to biochemical failure was classified as ≤ 18 or >18 months from the end of all therapy to the date of biochemical failure (BF). Kaplan-Meier methods and Cox proportional hazards regression were used to evaluate the prognostic value of IBF ≤ 18 months for distant metastasis (DM) and prostate cancer-specific mortality (PCSM).
RESULTS: Of 958 patients with a median follow-up of 63.2 months, 175 patients experienced BF. In those with BF, there were no differences in pretreatment clinical characteristics between the EBRT and CMRT groups, except for a higher proportion of patients with GS 8-10 in the CMRT group (70% vs 52%, P=.02). Median IBF after all therapy was 24.0 months (interquartile range 9.6-46.0) in the EBRT group and 18.9 months (interquartile range 9.2-34.5) in the CMRT group (P=.055). On univariate analysis, IBF ≤ 18 months was associated with increased risk of DM and PCSM in the entire cohort and the individual EBRT and CMRT groups. On multivariate analysis, only GS 9-10 and IBF ≤ 18 months, but not the radiation therapy regimen or ADT use, predicted DM (hazard ratio [HR] 3.7, P< .01, 95% confidence interval [CI] 1.4-10.3 for GS 9-10; HR 3.9, P< .0001, 95% CI 2.4-6.5 for IBF ≤ 18 months) and PCSM (HR 14.8, P<.009, 95% CI 2.0-110 for GS 9-10; HR 4.4, P< .0001, 95% CI 2.4-8.1 for IBF ≤ 18 months).
CONCLUSIONS: Short IBF was highly prognostic for higher DM and PCSM in patients with HiRPCa. The prognostic value of IBF for DM and PCSM was not affected by the radiation therapy regimen or ADT use.
Written by:
Shilkrut M, McLaughlin PW, Merrick GS, Vainshtein JM, Feng FY, Hamstra DA. Are you the author?
Department of Radiation Oncology, University of Michigan Health System, Ann Arbor, Michigan.
Reference: Int J Radiat Oncol Biol Phys. 2013 May 9. pii: S0360-3016(13)00350-7.
doi: 10.1016/j.ijrobp.2013.03.028
PubMed Abstract
PMID: 23664325
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