Department of Radiation Oncology, Fox Chase Cancer Center, Philadelphia, PA.
To correlate tumor oxygenation status with long-term biochemical outcome after prostate brachytherapy.
Custom-made Eppendorf Po2 microelectrodes were used to obtain Po2 measurements from the prostate (P), focused on positive biopsy locations, and normal muscle tissue (M), as a control. A total of 11,516 measurements were obtained in 57 men with localized prostate cancer immediately before prostate brachytherapy was given. The Eppendorf histograms provided the median Po2, mean Po2, and % < 5 mm Hg or < 10 mm Hg. Biochemical failure (BF) was defined using both the former American Society of Therapeutic Radiation Oncology (ASTRO) (three consecutive raises) and the current Phoenix (prostate-specific antigen nadir + 2 ng/mL) definitions. A Cox proportional hazards regression model evaluated the influence of hypoxia using the P/M mean Po2 ratio on BF.
With a median follow-up time of 8 years, 12 men had ASTRO BF and 8 had Phoenix BF. On multivariate analysis, P/M Po2 ratio < 0.10 emerged as the only significant predictor of ASTRO BF (p = 0.043). Hormonal therapy (p = 0.015) and P/M Po2 ratio < 0.10 (p = 0.046) emerged as the only independent predictors of the Phoenix BF. Kaplan-Meier freedom from BF for P/M ratio < 0.10 vs. ≥0.10 at 8 years for ASTRO BF was 46% vs. 78% (p = 0.03) and for the Phoenix BF was 66% vs. 83% (p = 0.02).
Hypoxia in prostate cancer (low mean P/M Po2 ratio) significantly predicts for poor long-term biochemical outcome, suggesting that novel hypoxic strategies should be investigated.
Turaka A, Buyyounouski MK, Hanlon AL, Horwitz EM, Greenberg RE, Movsas B. Are you the author?
Reference: Int J Radiat Oncol Biol Phys. 2011 Oct 8. Epub ahead of print.