Circulating tumor cells predict survival benefit from treatment in metastatic castration-resistant prostate cancer.
OBJECTIVE
A method for enumerating circulating tumor cells (CTC) has received regulatory clearance. The primary objective of this prospective study was to establish the relationship between posttreatment CTC count and overall survival (OS) in castration-resistant prostate cancer (CRPC). Secondary objectives included determining the prognostic utility of CTC measurement before initiating therapy, and the relationship of CTC to prostate-specific antigen (PSA) changes and OS at these and other time points.


METHODS
Blood was drawn from CRPC patients with progressive disease starting a new line of chemotherapy before treatment and monthly thereafter. Patients were stratified into predetermined Favorable or Unfavorable groups (<5 and > or =5 CTC/7.5mL).


RESULTS
Two hundred thirty-one of 276 enrolled patients (84%) were evaluable. Patients with Unfavorable pretreatment CTC (57%) had shorter OS (median OS, 11.5 versus 21.7 months; Cox hazard ratio, 3.3; P < 0.0001). Unfavorable posttreatment CTC counts also predicted shorter OS at 2 to 5, 6 to 8, 9 to 12, and 13 to 20 weeks (median OS, 6.7-9.5 versus 19.6-20.7 months; Cox hazard ratio, 3.6-6.5; P < 0.0001). CTC counts predicted OS better than PSA decrement algorithms at all time points; area under the receiver operator curve for CTC was 81% to 87% and 58% to 68% for 30% PSA reduction (P = 0.0218). Prognosis for patients with (a) Unfavorable baseline CTC who converted to Favorable CTC improved (6.8 to 21.3 months); (b) Favorable baseline CTC who converted to Unfavorable worsened (>26 to 9.3 months).


CONCLUSIONS
CTC are the most accurate and independent predictor of OS in CRPC. These data led to Food and Drug Administration clearance of this assay for the evaluation of CRPC.
de Bono
Johann S
JS
Section of Medicine, Institute of Cancer Research, Royal Marsden Hospital, Downs Road, Sutton, Surrey, United Kingdom. jdebono@icr.ac.uk
Scher
Howard I
HI
Montgomery
R Bruce
RB
Parker
Christopher
C
Miller
M Craig
MC
Tissing
Henk
H
Doyle
Gerald V
GV
Terstappen
Leon W W M
LW
Pienta
Kenneth J
KJ
Raghavan
Derek
D
D000368:Aged; D000369:Aged, 80 and over; D000465:Algorithms; D002369:Castration; D018450:Disease Progression; D019008:Drug Resistance, Neoplasm; D006801:Humans; D008297:Male; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009360:Neoplastic Cells, Circulating / Q000378:metabolism*; D011379:Prognosis; D016016:Proportional Hazards Models; D011471:Prostatic Neoplasms / Q000097:blood* / Q000401:mortality / Q000473:pathology*; D013997:Time Factors; D016896:Treatment Outcome