A retrospective analysis of the relationship between changes in serum PSA,palliative response and survival following systemic treatment in a Canadian randomized trial for symptomatic hormone-refractory prostate cancer

Background: To investigate the relationship between changes in serum PSA, p alliative response and survival following systemic treatment for symptomati c hormone-refractory prostate cancer (HRPC). Patients and methods: A retrospective review of 161 patients, treated with mitoxantrone and prednisone (M + P) (n = 80), or prednisone alone (P) (n = 81) from a Canadian randomized phase III clinical trial. PSA response was d efined by greater than or equal to 50% decline compared to baseline. Pallia tive response was defined by the primary and secondary endpoints of the tri al. All responses were required to be maintained on two visits at least thr ee weeks apart. The Cox proportional hazards model and a landmark analysis (at nine weeks) were used to evaluate survival differences between PSA resp onders and non-responders. Results: Using an intent-to-treat analysis in which patients with missing P SA data are considered non-responders, 34% of M + P and 11% of P patients a chieved a PSA response (P = 0.0001). Nineteen of thirty-six (53%) patients with PSA response and twenty-six of ninety (29%) patients without PSA respo nse achieved a palliative response (P= 0.001 Chi-square test, phi coefficie nt = 0.28). From the landmark analysis, PSA responders had longer survival than non-responders (P= 0.009). In multivariate analysis, better performanc e status, higher hemoglobin and PSA response (P < 0.001) predicted for surv ival, but palliative response did not (P = 0.11). Conclusions: There is significant but imperfect statistical association bet ween PSA response and palliative response. PSA response was associated with longer survival. Patients treated with M + P were more likely to achieve a PSA response and a palliative response than those treated with P.