Prostate-specific antigen growth rate constant after first-line cytotoxic chemotherapy in metastatic castration-resistant prostate cancer: a monoinstitutional experience.
OBJECTIVE
Validation in clinical practice, after first-line chemotherapy (CT) of metastatic castration-resistant prostate cancer (PC), of prostate-specific antigen growth rate constant logarithm (PSA-G), calculated by a formula developed by Stein et al. in comparison with PSA decrease (PSA-D), calculated as recommended by PCWG2.


METHODS
This study is a retrospective monoinstitutional assessment of PSA-G and PSA-D after 12 weeks from the beginning of first-line cytotoxic CT in 49 patients with metastatic castration-resistant PC treated from 2006 to 2011, and whose pre-CT PSA and post-CT PSA determinations have been measured at specific time points. The 12-week PSA was measured at 80 to 91 days from the beginning of CT.


RESULTS
PSA-G exhibited a significant correlation with overall survival by Mann-Whitney U test and by linear regression, whereas PSA-D did only at the first test. After multivariate analysis, PSA-G was the only posttreatment measure to predict overall survival.


CONCLUSIONS
PSA-G appears a reliable surrogate end point after first-line cytotoxic CT outside of clinical trials. A cutoff value of PSA-G post-CT higher than-2.4 could be considered suggestive for moving to another treatment.
Division of Medical Oncology, "G. Borea" Hospital, Sanremo, Italy. Electronic address: g.colloca@katamail.com.
Giuseppe
G
Colloca
Division of Medical Oncology, "G. Borea" Hospital, Sanremo, Italy.
Antonella
A
Venturino
Division of Medical Oncology, "G. Borea" Hospital, Sanremo, Italy.
Gianfranco
G
Addamo
Division of Medical Oncology, "G. Borea" Hospital, Sanremo, Italy.
Riccardo
R
Ratti
Division of Medical Oncology, "G. Borea" Hospital, Sanremo, Italy.
Zaira
Z
Coccorullo
Division of Medical Oncology, "G. Borea" Hospital, Sanremo, Italy.
Graziano
G
Caltabiano
Laboratorio Analisi, "G. Borea" Hospital, Sanremo, Italy.
Giorgio
G
Viale
Division of Medical Oncology, "G. Borea" Hospital, Sanremo, Italy.
Domenico
D
Guarneri
D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009362:Neoplasm Metastasis; D017063:Outcome Assessment, Health Care / Q000706:statistics & numerical data; D016016:Proportional Hazards Models; D017430:Prostate-Specific Antigen / Q000097:blood*; D064129:Prostatic Neoplasms, Castration-Resistant / Q000097:blood* / Q000188:drug therapy* / Q000473:pathology; D012189:Retrospective Studies; D016019:Survival Analysis; D013997:Time Factors
D000970:Antineoplastic Agents; D017430:Prostate-Specific Antigen
Chemotherapy; Growth rate constant; Prostate cancer; Surrogate end point