30-year extrapolations of overall survival (OS) and metastasis-free survival (MFS) from the SPCG-4 trial of radical prostatectomy (RP) versus watchful waiting (WW) in patients (pts) with early prostate cancer (ePCa).

Abstract

e16597 Background: Bill-Axelson et al (NEJM, 2014) reported 18 year (y) mortality and metastasis (mets) data on ePCa pts randomized in the SPCG-4 trial to RP (n = 347) vs WW (n = 348) for all pts and by age < 65y (nRP= 157 nWW= 166) vs ≥65y (nRP= 190 nWW= 182). Using the 18y data, we estimated the cumulative incidence, OS and MFS curves, and absolute risk reduction (ARR) for death and mets up to 30y for all pts and pts < 65y vs ≥65y. Methods: Published 18y SPCG-4 cumulative incidence curves for death and mets were digitized and parametric regression models were tested to fit the data. From these we estimated, for death and mets, the respective 30y cumulative incidences, OS and MFS curves with 95%CI; and ARR. ARRs for < 65y and ≥65y were compared using the chi-squared test. Results: The exponential regression model fit the data best. Over the 18 to 30y period, OS in all pts decreased from .81 to .69 in RP and from .72 to .56 in WW; in pts < 65y from .81 to .69 in RP and from .67 to .49 in WW; in pts ≥65y from .83 to .72 in RP and from .78 to .64 in WW. Over the same period, MFS in all pts decreased from .81 to .69 in RP and from .73 to .56 in WW; in pts < 65y from .81 to .69 in RP and from .67 to .49 in WW; in pts ≥65y from .78 to .64 in RP and from .75 to .59 in WW. OS and MFS 95%CI curves overlapped in pts ≥65y but not in pts < 65y. ARRs for death and mets of RP over WW are shown below by 2y interval. ARRs for death and mets were statistically different in pts < 65y but not in pts ≥65y. Conclusions: Extrapolated to 30y post randomization, RP shows better gains in OS and MFS over WW. RP is associated with significant reductions of death and mets: 19 more surviving pts and 20 more metastasis free pts per 100 pts among pts < 65y but not among pts ≥65y. These data enable clinicians to provide ePCA pts considering RP vs WW with up to 30y prognostic information. This facilitates informed patient decision making, especially among those age < 65y. [Table: see text]