Prostate-specific antigen doubling time before onset of chemotherapy as a predictor of survival for hormone-refractory prostate cancer patients.
BACKGROUND
We evaluated the possible use of prostate-specific antigen doubling time (PSA-DT) before chemotherapy initiation as a surrogate marker of survival in hormone-refractory prostate cancer (HRPC) patients.


METHODS
Data from 250 consecutive metastatic HRPC patients treated with chemotherapy between February 2000 and November 2006 were retrospectively analysed. At least three PSA assays were required within 3 months before chemotherapy. PSA-DT was calculated as ln 2 divided by the slope of the log PSA line, and the difference between two log PSA levels was divided by the time interval. The primary endpoint was overall survival (OS). Survival rates according to PSA-DT were stratified on chemotherapy regimen. Multivariate Cox regression analysis was performed to isolate the impact of PSA-DT on OS, controlling for associate prognostic covariates.


RESULTS
Patients received docetaxel- (82%) or mitoxantrone-based chemotherapy. The median PSA-DT was 45 days (range 4.7-1108 days). There were 174 deaths (70%). The median survival was 16.5 months (95% confidence interval [CI] = 12.5-20.5) and 26.4 months (95% CI = 20.3-32.4) for patients with a PSA-DT < 45 and > or =45 days, respectively. In the multivariate setting, the adjusted hazard ratio (HR) was 1.39 (95% CI = 1.03-1.89; P = 0.04), stratified by chemotherapy regimen.


CONCLUSIONS
A short PSA-DT before onset of chemotherapy in HRPC patients was associated with an increased risk of death. This could be useful as a stratification parameter in trials with new drugs in a metastatic setting.
Oudard
S
S
Georges Pompidou European Hospital, Medical Oncology Department, Paris, France. stephane.oudard@egp.aphp.fr
Banu
E
E
Scotte
F
F
Banu
A
A
Medioni
J
J
Beuzeboc
P
P
Joly
F
F
Ferrero
J-M
JM
Goldwasser
F
F
Andrieu
J-M
JM
D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000008:administration & dosage*; D014408:Biomarkers, Tumor / Q000097:blood*; D015331:Cohort Studies; D016001:Confidence Intervals; D019008:Drug Resistance, Neoplasm; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009362:Neoplasm Metastasis; D009367:Neoplasm Staging; D011336:Probability; D011379:Prognosis; D017430:Prostate-Specific Antigen / Q000097:blood*; D011471:Prostatic Neoplasms / Q000097:blood / Q000188:drug therapy* / Q000401:mortality* / Q000473:pathology; D012189:Retrospective Studies; D018570:Risk Assessment; D016019:Survival Analysis; D013997:Time Factors; D016896:Treatment Outcome
D018931:Antineoplastic Agents, Hormonal; D014408:Biomarkers, Tumor; D017430:Prostate-Specific Antigen