Circulating tumour cells and hypercoagulability: a lethal relationship in metastatic breast cancer

Abstract

Purpose: Circulating tumour cells (CTCs) are a marker of poor prognosis and are associated with increased risk of venous thromboembolism in metastatic breast cancer (MBC). We aimed to determine if the presence of CTCs and plasma markers of hypercoagulability [thrombin-antithrombin III (TAT), fibrinogen and D-dimer] are biomarkers of survival in MBC.

Methods/patients: In a prospective study of MBC patients, CTC (CellSearch^®) enumeration and plasma TAT, fibrinogen and D-dimer measured prior to commencement of treatment for disease progression were correlated to overall survival.

Results: At study completion, of 50 MBC patients recruited (median age 59 years, range 36-82), 40 patients had died (median survival 417 days, range 58-2141). CTCs (≥ 1/7.5 ml) were identified in 16 patients (median number of cells per 7.5 ml, 3 (range 1-31) and were associated with systemic hypercoagulability (medians TAT: 8.1 vs. 5.2 ng/ml, p = 0.03; fibrinogen: 4.3 vs. 3.1 g/l, p = 0.03; D-dimer: 1327 vs. 683 ng/ml, p = 0.0001). At 1 year, of 16 patients with ≥ 1 CTC, 7 had died (44%), compared to 5 of 26 (19%) patients in the no-CTC group. The presence of ≥ 1 CTC was associated with a trend for reduced overall survival (median 455 days vs. 614 days, p = 0.15). Plasma TAT inversely correlated with survival and was significantly higher in patients dying within 1 year (median 9.8 vs. 5.2 ng/ml, p = 0.004) whilst D-dimer showed a trend for reduced 1-year survival (median 1211 vs. 817 ng/ml, p = 0.06). MBC patients with combined high D-dimer (≥ 895 ng/ml) and CTC positivity (≥ 1/7.5 ml whole peripheral blood) had significantly reduced survival (p = 0.04).

Conclusions: The correlation between CTCs, hypercoagulability and reduced survival in MBC suggests the coagulation system supports tumour cell metastasis and is, therefore, a potential therapeutic target.

Keywords: CTC; Coagulation; D-Dimer; Fibrinogen; Survival; TAT.

Fig. 1

Circulating tumour cells (CTCs) are associated with increased coagulation plasma markers in metastatic breast cancer. CTC number in 7.5 ml peripheral whole blood samples enumerated by the CellSearch technology compared to plasma coagulation markers a thrombin–antithrombin III complex (TAT), b fibrinogen and c, dd-dimer in metastatic breast cancer (MBC) patients. Unpaired two-tailed t tests comparing Log₂ transformed raw coagulation marker concentrations + 1 to CTC group, *p < 0.05, **p < 0.01, ***p < 0.001. Error bars show standard error of the mean (SEM); n number of MBC patients in each group, TAT thrombin–antithrombin III complex, CTC circulating tumour cell

Fig. 2

Trend for reduced overall survival in circulating tumour cell (CTC)-positive metastatic breast cancer patients. CTC number in 7.5 ml peripheral whole blood samples enumerated by the CellSearch technology was enumerated in metastatic breast cancer (MBC) patients. Log-rank (Mantel–Cox) testing compared survival in days from study entry in CTC-positive compared to CTC-negative patients. CTC positive defined as ≥ 1/7.5 ml. Assumption of proportionality was verified based on Schoenfeld residuals; n number of MBC patients in each group, CTC circulating tumour cell

Fig. 3

Coagulation plasma markers TAT and d-dimer are associated with poorer survival in metastatic breast cancer. Coagulation markers thrombin–antithrombin III complex (TAT) and d-dimer were quantified by immunoassay in metastatic breast cancer (MBC) patient plasma samples. a TAT, cd-dimer: unpaired two-tailed t tests of Log₂ transformed raw coagulation marker concentrations compared to survival groups, **p < 0.01. Error bars show standard error of the mean (SEM). b TAT, dd-dimer: log-rank (Mantel–Cox) tests comparing survival in days from study entry in these coagulation markers dichotomised around the median values (TAT 5.9 mg/ml, d-dimer 895 ng/ml) were carried out, **p < 0.01. Assumption of proportionality was verified based on Schoenfeld residuals; n number of MBC patients in each group, TAT thrombin–antithrombin III complex

Fig. 4

The combined presence of a high d-dimer and circulating tumour cell positivity is associated with reduced survival in metastatic breast cancer. Survival in patients with CTC positive (≥ 1 CTCs/7.5 ml) and high d-dimer (≥ 895 ng/ml) (red line, n = 13) was compared to all other patients (blue line, n = 26). A log-rank (Mantel–Cox) test comparing survival in days from study entry in the shown CTC/coagulation marker groups was performed. Assumption of proportionality was verified based on Schoenfeld residuals; n number of MBC patients in each group, CTC circulating tumour cell