Stable versus partial response in advanced prostate cancer.

Stable response to therapy in patients with advanced prostate cancer, as experienced in clinical trials of the National Prostatic Cancer Project (NPCP), has been reexamined. Data from ten complete trials totaling over 1,300 patients have been examined for survival patterns within categories of response to therapy. Survival patterns, both for all patients and for those alive at 12 weeks, were significantly poorer for patients categorized as progressors after 12 weeks on treatment than for those categorized as stable or as partial regressions. Furthermore, comparisons of survival patterns for those patients categorized as stable or partial regression revealed no statistically significant differences between them. The similarity of survival for the stable and partial regression categories indicates that the stable category represents more than a segment of the population with slowly progressing disease and can be taken as an indicator of response to therapy.