Abstract P2-02-08: Initial circulating tumor cell count and venous thrombosis-free interval in the course of metastatic breast cancer

Abstract

Abstract Background: Circulating tumor cells (CTC) count is a major prognostic factor in metastatic breast cancer. It has been also reported to be associated with venous thrombosis in short-term studies on advanced metastatic breast cancer patients. Methods: We assessed whether an early CTC detection (CellSearch®), before the start of the first line chemotherapy, impacts Thrombosis-Free Interval during the whole course of metastatic breast cancer. Electronic medical files of all patients included in the large prospective IC 2006-04 CTC detection study (NCT00898014, Pierga et al, Ann Oncol 2012) and treated at Institut Curie (Paris, France) were manually and automatically searched for thrombosis events in the course of their metastatic breast cancer. Superficial venous thromboses were not taken into account.Thrombosis-Free Interval (TFI) was defined as the first event occuring between venous or arterial thrombosis. Results: In the 142 patients studied, with a median follow-up of 64 months [25-81 months], venous (deep venous thrombosis, pulmonary embolism, catheter thrombosis and portal vein thrombosis) and arterial thrombosis occurred in 21.8% and 4.2% of patients, respectively. Twenty-four (30%) of the 80 patients with ≥1 CTC/7.5ml of blood before the start of first line chemotherapy experienced at least one thrombotic events in the course of their disease, while only 10 (16%) of the 62 CTC-negative patients experienced a similar event (p=0.06). Baseline positive CTC was associated with a higher risk of experiencing a venous or arterial thrombosis (TFI: HR=2.6 [1.2-5.5], p=0.009). The median TFI was 64 months in CTC-positive patients and not reached in CTC-negative patients. Among the other patients characteristics tested at baseline, Performance Status (PS=1 vs PS=0: HR=0.85 [0.4-1.9], p=NS; PS=2 or 3 vs PS=0: HR=3.7 [1.5-8.7], p=0.003) and LDH levels at baseline (LDH>UNL vs LDH<UNL HR=2.4 [1.2-4.9], p=0.012) were also associated with TFI. Conclusions: Metastatic breast cancer patients with ≥1 CTC before the start of chemotherapy are at higher risk of venous thrombosis; the clinical relevance of thrombo-prophylaxis should be investigated in this population. Citation Format: Beinse G, Berger F, Cottu PH, Dujaric M-E, Kriegel I, Guilhaume M-N, Dieras V, Beuzeboc P, Pierga J-Y, Bidard F-C. Initial circulating tumor cell count and venous thrombosis-free interval in the course of metastatic breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P2-02-08.