Assessing PSA levels as prognostic of overall survival (OS) in men with metastatic hormone-sensitive prostate cancer (mHSPC).

Abstract

5070 Background: Prior data have shown that prostate specific antigen (PSA) ≤ 0.2 ng/dL at 6-7 months with androgen deprivation therapy (ADT) with testosterone suppression (TS) alone is prognostic of OS. We hypothesized that PSA ≤0.1 ng/dL at 7 months would be a stronger prognostic for OS in men with mHSPC treated with TS alone. This hypothesis was investigated by the STOPCAP M1 collaborators. Methods: Individual patient data from 13 eligible randomized trials comparing treatment regimens (TS or TS + docetaxel in the control or research arms in mHSPC trials were utilized. Landmark survival analyses were performed at 7 months after ADT initiation. Overall survival was computed as the time from 7 months after start of initial TS to death or date of last follow for patients who started TS prior to randomization or 7 months after randomization to death or date last follow-up for patients who started TS after randomization. PSA measurements between 4-7 months after ADT were selected and cut off-points of PSA ≤0.2, 0.2-4, and >4 ng/dL or PSA ≤0.1, 0.1-0.2, 0.2-4, and >4 ng/dL were considered. The proportional hazards model was utilized to explore the prognostic significance of PSA levels in predicting OS adjusting for treatment in all patients and patients who were enrolled on docetaxel trials. Results: IPD from 5,438 patients randomized 1994-2012 from 13 trials were pooled. At 7 months, the proportion of patients who had PSA≤0.1 and PSA ≤0.2 were 18.1% and 26.1%. The median OS in patients who experienced PSA ≤0.1 and PSA≤0.2 and in patients enrolled on docetaxel trials are presented in the table below. The hazard ratios (HR) for death for PSA≤0.1 and PSA≤0.2 vs. those PSA>4 at 4-7 months were 0.26 and 0.27, respectively. In patients enrolled on docetaxel, HRs for death for PSA≤0.1 and PSA≤0.2 vs. those PSA>4 at 7 months were 0.35 and 0.34, respectively. Conclusions: PSA≤0.1 and PSA≤0.2 at 7 months have similar prognostic value of OS in men with mHSPC treated with weak ADT (TS alone) without and with docetaxel. Clinical trial information: NCT00309985 ; NCT00268476 ; NCT00104715 ; NCT00079001 ; NCT00002651 ; NCT00685646 . [Table: see text]