Prostate specific antigen doubling time (PSADT) in patients with hormone refractory prostate cancer (HRPC) undergoing docetaxel chemotherapy as a predictor of overall survival

Abstract

15556 Background: Few data correlating PSADT and overall survival(OS) in patients with HRPC undergoing chemotherapy exist. Docetaxel has recently been shown to significantly improve OS in patients with HRPC, but with significant toxicities. The decision of when to initiate chemotherapy is not well defined, but the presence of symptoms or narcotic use has widely been used to indicate this. The current retrospective study aims to identify a specific PSADT that independently correlates with OS in HRPC patients receiving docetaxel. Methods: A retrospective review of all patients with HRPC receiving docetaxel from 2001 to 2006 was performed. Androgen independent prostate cancer (AIPC) was defined as the time of a rising PSA despite castrate levels of testosterone. Variables evaluated from time of AIPC to initiation of chemotherapy included PSA, PSADT, hemoglobin, alkaline phosphatase, Gleason score. Time to AIPC was also evaluated. Patients who had pain or were on narcotics at the time of chemotherapy initiation were considered symptomatic. OS was calculated for both time from AIPC to death or last follow-up, and for time from chemotherapy to death or last follow-up. Results: 50 patients treated with docetaxel for HRPC were evaluated. Median OS was 32 months, and median survival from start of docetaxel was 14 months. There was no difference in OS between symptomatic or asymptomatic patients. A PSADT of >2 mos was significantly correlated with improved median OS (p= 0.005). Univariate analyses of all other factors were not significant. Furthermore, in patients with a favorable outcome ( >14 mos) from start of docetaxel, a PSADT of >2 mos was a significant predictor of improved survival (p=0.02). Conclusions: This is the first study to evaluate PSADT in HRPC patients receiving docetaxel exclusively. Our data shows that a shorter PSADT (<2 mos) significantly predicts shorter OS. Symptoms or narcotic use did not correlate with OS. Taken together, these data suggest that a PSADT of <2 mos may be a better predictor of when to initiate chemotherapy than symptoms or narcotic use. The lack of significant correlation between the other variables and OS may further suggest the robustness of PSADT as a predictive variable. No significant financial relationships to disclose.