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Mark K. Buyyounouski M.D., M.S., Alexandra L. Hanlon, Ph.D.,
Eric M. Horw1tz, M.D., And Alan Pollack M.D.~ Ph.D.
Department. of Radiation Oncology, Fox Chase Cancer Center,
Philadelphia, PA
Purpose: Few biochemical parameters have been related to
mortality. The present study examined the clinical utility of the
interval to biochemical failure (IBF) as a prognostic factor for
distant metastasis (DM) and prostate cancer-specific mortality (PCSM)
after radiotherapy.
Methods and Materials: The study group consisted of 211
Tlc-T3Nx-N0M0 patients who had experienced BF among 1,174 men
treated with three-dimensional conformal radiotherapy alone.
Biochemical failure was defined as post-treatment prostate-specific
antigen (PSA) level of at, or greater than the PSA nadir plus ng/mL.,Cox
proportional hazards modeling was used to identify independent
predictors of DM and PCSM on multivariate analysis
Results: An IBF of <18 months was independently predictive
for DM (p=0.008) as was a Gleason score of 7-10 (p=0.0005), PSA
nadir > 2ng/mL(p=0.04), and decreasing radiation dose (p=0.02) on
multivariate analysis, including increasing pretreatment PSA level,
PSA nadir >2.5ng/mL, PSA doubling time of <3, and Stage T3 disease.
An IBF of <18 months was the only predictor of PCSM (p=0.0003) in
the same model. The actuarial 5-year DM rate for an IBF of <18 VS.
>18 months was 52% vs. 20% (p=0.0001),and the actuarial PCSM rate
was 36% vs. 6%, respectively (p=0.0001).
Conclusion: The IBF is an important descriptor of the PSA
kinetics after radiotherapy to identify men at high risk Of clinical
failure and death. A IBF of <.18 months could aid in selecting men
for early, aggressive salvage therapy or participation in a clinical
trial. 2008 Elsevier Inc.
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