Hi. Scher et al., Post-therapy serum prostate-specific antigen level and survival in patients with androgen-independent prostate cancer, J NAT CANC, 91(3), 1999, pp. 244-251
Background: With an hypothesis that post-chemotherapy changes in serum pros
tate-specific antigen (PSA) levels might serve as a surrogate marker for as
sessing prostate cancer outcome (i.e., survival), we studied the relationsh
ip between pretherapy and post-therapy prognostic factors and survival in p
atients with androgen-independent prostate cancer. Methods: A prognostic mo
del for survival based on pretherapy and post-therapy parameters was develo
ped from the clinical data on 254 patients with androgen-independent prosta
te cancer treated with 11 different protocol therapies at Memorial Sloan-Ke
ttering Cancer Center. The model was validated by use of an independent dat
aset of 541 patients enrolled in two randomized phase III trials. Results:
In multivariate analysis, a post-therapy decline in PSA levels of 50% achie
ved in 12 weeks was a statistically significant factor associated with surv
ival (two-sided P = .0012). A similar outcome was obtained with the use of
an 8-week time frame. Elevated pretherapy level of serum lactate dehydrogen
ase (two-sided P = .0001), lower pretherapy level of hemoglobin (P = .0001)
, and younger age (two-sided P = .0430) had a statistically significant neg
ative impact on outcome. Median survival times were 23, 17, and 9 months fo
r low-, intermediate-, and high-risk groups of patients defined by the prog
nostic model, respectively. Conclusion: This study confirms the prognostic
value of a post-therapy decline in PSA of 50% or greater from baseline in r
elation to survival in patients with androgen-independent prostate cancer t
reated with a variety of therapies, Two consecutive determinations at 4-wee
k intervals can be used as an end point for efficacy in phase II trials of
therapies in this disease.