Buyyounouski MK et al. (2007) Interval to biochemical failure highly prognostic for distant metastasis and prostate cancer-specific mortality after radiotherapy. Int J Radiat Oncol Biol Phys 70: 59–66

Biochemical failure after initial treatment in patients with prostate cancer is an indicator that further treatment may be required, but deciding for whom and how quickly is sometimes problematic. In this study, Buyyounouski et al. investigated whether the interval to biochemical failure (IBF) might be a better predictor of clinical outcome than the American Society of Therapeutic Radiation Oncology (ASTRO) definition, and whether IBF could be used to predict for more-aggressive disease.

A total of 1,174 patients with prostate cancer treated by three-dimensional conformal radiotherapy only were examined, and 211 were identified as having biochemical failure (i.e. post-treatment prostate-specific antigen [PSA] level of ≥PSA nadir plus 2 ng/ml—the current ASTRO consensus definition). Statistical analysis revealed that an IBF of <18 months was an independent predictor of distant metastasis. Other independent predictors of distant metastasis included a Gleason score of 7–10, a PSA nadir of ≥2 ng/ml, and decreasing radiation dose. In addition, multivariate analysis showed that an IBF of <18 months was an independent predictor of prostate-cancer-specific mortality.

The authors conclude that the IBF could be used to identify men at high risk of clinical failure and death. Those with an IBF of less than 18 months might benefit from aggressive salvage therapy or from participation in a clinical trial.