Journal of Clinical Oncology, 2006 ASCO Annual Meeting Proceedings (Post-Meeting Edition).
Vol 24, No 18S (June 20 Supplement), 2006: 4517
© 2006 American Society of Clinical Oncology

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Abstract

Absolute PSA value after androgen deprivation (AD) is a strong independent predictor of survival in new metastatic (D2) prostate cancer (PCa): Data from Southwest Oncology Group Trial 9346 (INT-0162)

University of Michigan, Ann Arbor, MI; SWOG, Seattle, WA; Devine-Tidewater Urology, Norfolk, VA; University of Colorado Health Sciences Center, Aurora, CO; University of Washington, Seattle, WA; University of Wisconsin, Madison, WI; Marmara University, Istanbul, Turkey; University of California San Francisco, San Francisco, CA; University of Calgary, Calgary, AB, Canada; Cleveland Clinic, Cleveland, OH

4517

Background: PSA is a biomarker for monitoring disease activity in PCa. It is not well established if absolute PSA values achieved after AD is prognostic in patients (pts) with new D2 PCa. Methods: Hormone naive D2 pts with baseline PSA 5ng/mL are treated with 7 months (ms) AD induction. Pts achieving PSA-n (PSA 4.0 ng/ml that is stable or declining on ms 6 and 7) are randomized to continuous vs. intermittent AD on month 8. To be eligible for this analysis (approved by Data Safety Monitoring Committee), pts had to have a prestudy PSA with at least 2 subsequent PSAs during induction and be registered at least 1 year prior to analysis date. Survival was defined from 8 months to death due to any cause. Associations were evaluated by proportional hazards regression models. P0.05 was statistically significant. Results: Of the first 1,395 registered pts, 1345 were eligible for this analysis. Median age was 70 years, median baseline PSA 76.1 ng/mL, 38% had bone pain (BP) and 47 % had Gleason sum (GS) > 7. Median number of on-study PSAs during induction was 5 (range: 2 -18). Of the 1,345 pts, 1134 achieved PSA-n with 965 maintaining PSA-n at end of induction. Of those achieving PSA-n, 604 (45% of all pts) had an undetectable PSA (PSA-u, 0.2 ng/mL) at end of induction. In multivariate analysis, 4 significant independent risk factors were associated with post-induction survival: Performance status, GS, BP, and being randomized. After adjustment for these factors, pts who had a PSA-n at the end of induction but not PSA-u had less than half the risk of death (RoD) as those who did not have PSA-n (HR: 0.41; 95% CI 0.32, 0.54, p < 0.001), and pts with PSA-u had about one-quarter the RoD as pts with no PSA-n (HR: 0.26; 95% CI 0.20, 0.35, p < 0.001). After adjustment for covariates, pts with PSA-u had significantly better survival than those with only PSA-n at end of induction (p < 0.001). The median overall survival was 13 ms for the 383 not normalized (95% CI: 11 to 16 ms), 44 ms for the 360 pts normalized but not undetectable (95% CI: 39 to 55 ms), and 75 ms for the 602 pts with PSA-u (95% CI: 62, 91 ms). Conclusion: Achieving a PSA-n or PSA-u after 7 ms of AD is a strong predictor of survival and should be used to tailor future trial design in new D2 pts.

Author Disclosure

Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Funding Expert Testimony Other Remuneration AstraZeneca AstraZeneca AstraZeneca

Abstract presentation from the 2006 ASCO Annual Meeting