Circulating tumor cells, disease progression, and survival in metastatic breast cancer.
BACKGROUND
We tested the hypothesis that the level of circulating tumor cells can predict survival in metastatic breast cancer.


METHODS
In a prospective, multicenter study, we tested 177 patients with measurable metastatic breast cancer for levels of circulating tumor cells both before the patients were to start a new line of treatment and at the first follow-up visit. The progression of the disease or the response to treatment was determined with the use of standard imaging studies at the participating centers.


RESULTS
Outcomes were assessed according to levels of circulating tumor cells at baseline, before the patients started a new treatment for metastatic disease. Patients in a training set with levels of circulating tumor cells equal to or higher than 5 per 7.5 ml of whole blood, as compared with the group with fewer than 5 circulating tumor cells per 7.5 ml, had a shorter median progression-free survival (2.7 months vs. 7.0 months, P<0.001) and shorter overall survival (10.1 months vs. >18 months, P<0.001). At the first follow-up visit after the initiation of therapy, this difference between the groups persisted (progression-free survival, 2.1 months vs. 7.0 months; P<0.001; overall survival, 8.2 months vs. >18 months; P<0.001), and the reduced proportion of patients (from 49 percent to 30 percent) in the group with an unfavorable prognosis suggested that there was a benefit from therapy. The multivariate Cox proportional-hazards regression showed that, of all the variables in the statistical model, the levels of circulating tumor cells at baseline and at the first follow-up visit were the most significant predictors of progression-free and overall survival.


CONCLUSIONS
The number of circulating tumor cells before treatment is an independent predictor of progression-free survival and overall survival in patients with metastatic breast cancer.
Cristofanilli
Massimo
M
Department of Breast Medical Oncology, University of Texas M.D. Anderson Cancer Center, Houston, TX 77030, USA. mcristof@mdanderson.org
Budd
G Thomas
GT
Ellis
Matthew J
MJ
Stopeck
Alison
A
Matera
Jeri
J
Miller
M Craig
MC
Reuben
James M
JM
Doyle
Gerald V
GV
Allard
W Jeffrey
WJ
Terstappen
Leon W M M
LW
Hayes
Daniel F
DF
D001943:Breast Neoplasms / Q000097:blood / Q000401:mortality* / Q000473:pathology* / Q000628:therapy; D002469:Cell Separation; D018450:Disease Progression; D005260:Female; D006801:Humans; D008875:Middle Aged; D009362:Neoplasm Metastasis; D009360:Neoplastic Cells, Circulating; D016016:Proportional Hazards Models; D011446:Prospective Studies; D016019:Survival Analysis