1512 - Circulating Tumor Cells in Soft Tissue Sarcomas Patients

Abstract

ABSTRACT Introduction Soft tissue sarcomas (STSs) are an heterogeneous group of highly malignant mesenchymal tumors with only few recognised prognostic and predictive factors. Circulating tumor cells (CTCs) are considered a prognostic marker classically associated with poor prognosis in epithelial solid cancer patients. The purpose of this study was to explore the possibility to detect CTCs in blood samples of STSs metastatic patients. Methods Patients with histologically confirmed STSs and known metastases treated at Campus Bio-Medico Hospital of Rome from June 2011 to February 2012 were included. Blood was collected from patients who progressed on previous chemotherapy (1st, 2nd or 3rd line). All patients signed informed consent before phlebotomy. CTCs were assessed with CellSearchSystem (Veridex, USA). After immunomagnetic enrichment with an anti-Epcam-antibody, cells were labelled with anti-Ck8/18/19 and anti-CD45 antibodies to distinguish between epithelial cells and leukocytes. Wilcoxon rank-sum test was used to test for associations between CTC assay results and specific histotype, number of previous treatment, number and localization of metastatic disease sites. Results Twenty-three patients with metastatic STSs were evaluated. CTCs were detectable in 10/23 (43%) patients with CTC counts in the range of 0-4 cells/7.5 mL. The median number of CTCs was significantly lower in patients with only one site of metastasis compared to those with two or more metastatic sites (0 vs 2; P = 0.003). There was no statistically significant difference (P = 0.210) in median CTC counts between patients who received only a first line regimen (0, range 0-4) vs patients who previously received more anticancer therapies (1, range 0-3). Finally, no statistically significant correlation was identified between the number of CTCs and the histological grading evaluated according to the FNCLCC grading system (P = 0.468). Conclusions To our knowledge this is the first detection of circulating Epcam/Ck8/18/19+ cells in STSs patients, even if the identified circulating cells could be epithelial cells due to direct tumour invasion of the blood vessel from the surrounding tissue or tumor cells at the moment of mesenchymal-epithelial transition. Disclosure All authors have declared no conflicts of interest.