218P - Circulating tumor cells as a prognostic marker in advance colorectal cancer patients treated with cetuximab-containing salvage chemotherapy

Date 30 September 2012
Event ESMO Congress 2012
Session Poster presentation II
Topics Colon Cancer
Rectal Cancer
Translational Research
Presenter Satoshi Matsusaka
Authors S. Matsusaka1, Y. Kuboki1, M. Suenaga1, E. Shinozaki2, N. Mizunuma1, K. Hatake3
  • 1Gastroenterology, Cancer Institute Hospital, 135-8550 - Tokyo/JP
  • 2Medical Oncology, Cancer Institute Hospital, 135-8550 - Tokyo/JP
  • 3Hematology, Cancer Institute Hospital of JFCR, JP-135-8550 - Tokyo/JP

Abstract

Background

Circulating tumor cells (CTC) can be a predictive, or a prognosis marker in advance colorectal cancer (ACC) patients treated with chemotherapy plus targeted agents as front-line therapy. We assessed assessed the prognostic and predictive role of CTC in ACC patients treated with cetuximab (with or without irinotecan) who had been previously treated with a fluoropyrimidine, irinotecan, and oxaliplatin.

Material and methods

Between October 2008 and March 2011, 63 patients with KRAS wild-type ACC were treated with cetuximab as a third-line therapy at the Cancer Institute Hospital, providing written informed consent for CTC collection. We used CellSearch system for detection and EGFR expression for CTC. Patients were stratified into low (less than three CTC per 7.5ml of blood) or high (three or more CTC per 7.5ml of blood).

Results

A total of 63 patients were assessable for CTC analysis. Of the 63 patients with evaluable baseline CTC results, 19 patients (30%) had high CTC. The median number of CTC was one (range 0- 220, mean 7.28) at baseline. Patients with high CTCs had a shorter median overall survival (8.9 months) than those with low CTCs (15.3 months) [P < 0.005; HR 2.2 (95% CI 1.2–3.9)]. There was no significant difference in PFS between the two groups (PFS; HR 1.2). Of the 33 patients with positive CTC, 7 patients (21%) had EGFR-positive CTC, and 26 patients (79%) had EGFR-negative CTC. The concordance rate for EGFR between tumor and CTC was 30.5%.

Conclusion

High CTC count at baseline is a poor prognostic factor for OS in ACC patients treated with cetuximab-containing chemotherapy as salvage.

Disclosure

All authors have declared no conflicts of interest.