Gleason Grading, Biochemical Failure, and Prostate Cancer-Specific Death

Objectives: To examine the relationship between the recently defined Gleason grade groups and prostate cancer-specific mortality. Methods: If the probability of prostate cancer-specific death is symbolized as P(PSD), the probability of biochemical failure is symbolized as P(BF), and the probability of prostate cancer-specific death after biochemical failure is symbolized as P(PSD vertical bar BF), then the rules of probability provide a way to estimate P(PSD) as P(PSD) = P(PSD vertical bar BF) * P(BF) Using this model and data from the literature for P(PSD vertical bar BF) and P(BF), I estimate here values of P(PSD) for the five newly described Gleason grade groups. Results: The expected probability of prostate cancer-specific death is closely related to the new Gleason grade groups and ranges from a low of 0.014 for grade group 1 to a high of 0.15 for grade group 5. Conclusions: Although using the original study patient population may require years of additional follow-up to examine prostate cancer-specific mortality, the evidence available now indicates that these new Gleason grade groups relate to prostate cancer-specific mortality.