Prognostic significance of circulating tumour cells enumerated after filtration enrichment in early and metastatic breast cancer patients.
BACKGROUND
We previously found a higher incidence of circulating tumour cells (CTCs) in women with metastatic breast cancer compared to early disease. In this study, we present follow-up data to explore the prognostic significance of these findings.


METHODS
CTCs were quantified by immunostaining and direct visualization after centrifugation and filtration enrichment of peripheral blood from 131 patients. Time to progression (TTP) and overall survival (OS) were defined as interval from first blood sampling to first documented disease progression, or death respectively. Lifetime data was analysed using Kaplan-Meier method, log-rank test and Cox proportional hazards model.


RESULTS
Follow-up data is available for 123 patients. In early disease, median CTC>or=4 best distinguished patients with shorter TTP (p=0.05, log-rank test). In univariate analysis, tumour size, grade, lymphovascular invasion (LVI) and receptor status significantly related to TTP but none of the covariates related to OS. In multivariate analysis, T stage was the only independent predictor of TTP. In metastatic disease, median CTC>or=13 optimally identified patients with shorter TTP (p=0.01). In univariate analysis, median CTC level >or=13 and prior lines of chemotherapy predicted for TTP while in multivariate analysis, median CTC level >or=13 was the only significant independent prognostic factor (p=0.02). No relationship between CTC level and OS was found in this subgroup.


CONCLUSIONS
Median CTC level determined in the course of treatment predicts for TTP in metastatic breast cancer. In early breast cancer, an association was found between CTC level and TTP although this did not reach statistical significance (p=0.05).
Department of Medical Oncology, Sunnybrook and Women's College Health Sciences Centre, Toronto, Ontario, Canada. dmowns@nccs.com.sg
Nan Soon
NS
Wong
Harriette J
HJ
Kahn
Liying
L
Zhang
Stephanie
S
Oldfield
Lu-Ying
LY
Yang
Alexander
A
Marks
Maureen E
ME
Trudeau
D000328:Adult; D000368:Aged; D001943:Breast Neoplasms / Q000097:blood* / Q000175:diagnosis* / Q000188:drug therapy* / Q000473:pathology*; D018450:Disease Progression; D005260:Female; D005374:Filtration; D006801:Humans; D008875:Middle Aged; D015999:Multivariate Analysis; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D009360:Neoplastic Cells, Circulating / Q000378:metabolism* / Q000473:pathology*; D011379:Prognosis; D016016:Proportional Hazards Models; D016896:Treatment Outcome