Circulating epithelial tumor cells (CETC) during preoperative chemotherapy (CTX) of patients with gastric cancer.

Abstract

e21063 Background: we investigated CETC in blood samples accompanying a German multicenter phase II/III trial comparing perioperative CTX with epirubicin, cisplatin, 5-FU, leucovorin (ECF) every 3 weeks or 5-FU, leucovorin, oxaliplatin, docetaxel (FLOT) every 2 weeks. Methods: 7.5ml of anti-coagulated blood was drawn before the first and before the second course of CTX and after the end of preoperative CTX before surgery. After red blood cell lysis the white blood cells including the CETC were stained with a fluorescent labelled anti-epithelial antibody, positive events counted using an automated image analysis microscope and calculated per volume blood. Results: CETC were evaluable from 98 patients (FLOT: n=41; ECF: n=57). Characteristic response pattern to treatment were observed: Most patients (n=33 (81.5 %) from the FLOT arm and n=45 (79%) from the ECF arm) showed a decrease in CETC numbers during the first treatment course. Of these patients 11/33 (33%) in the FLOT arm and 24/45 (53%) in the ECF arm had a re-increase in cell numbers after chemotherapy (chi-square test p=.079). 11/11 (100% of patients with an initial increase in CETC in the FLOT arm subsequently showed decreasing CETC numbers whereas this was true only for 8/12 (66%) of the patients from the ECF arm (chi-square test p=.035). Conclusions: this is the first report on CETC during neoadjuvant CTX of gastric cancer. We have observed a rapid decrease in the number of CETC during CTX in the majority of patients in both arms. A re-increase under ongoing CTX was seen more frequently in patients receiving ECF. Whether the initial decrease of CETC correlates with tumor size reduction and subsequent difference in behaviour of CETC numbers during CTX translates into clinical outcome needs to be investigated in the frame of the ongoing German multicenter study.