A suitable setting to analyze factors that determine prognosis or treatment response in prostate cancer is an unbiased comparison of radical prostatectomy and watchful waiting as in the Scandinavian Prostate Cancer Group Trial number 4. In our previous presentation of 10-year results, we studied Gleason score, serum prostate-specific antigen (PSA) at diagnosis, and age at diagnosis as modifiers of the effect of radical prostatectomy on survival. Because overall prognostic information obtained by these parameters or by tumor stage was not provided in our publication, we now present these data in the two study arms separately.