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Case Reports in Oncological Medicine
Volume 2017 (2017), Article ID 6139634, 3 pages
Case Report

Clinical Application of Liquid Biopsy in Targeted Therapy of Metastatic Colorectal Cancer

1Gastroenterology, Department of Medicine, Goethe University Frankfurt, Frankfurt, Germany
2IMBL Medical Clinic, Universitätsklinikum Knappschaftskrankenhaus Bochum, Bochum, Germany
3Department of Medicine, Hematology, and Oncology, Ruhr-University of Bochum, Bochum, Germany

Correspondence should be addressed to Alexander Baraniskin

Received 15 November 2016; Accepted 25 December 2016; Published 23 January 2017

Academic Editor: Jose I. Mayordomo

Copyright © 2017 Jörg Trojan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Background. Colorectal cancers (CRC) shed DNA into blood circulation. There is growing evidence that the analysis of circulating tumor DNA can be effectively used for monitoring of disease, to track tumor heterogeneity and to evaluate response to treatment. Case Presentation. Here, we describe two cases of patients with advanced CRC. The first case is about a patient with no available tissue for analysis of RAS mutation status. Liquid biopsy revealed RAS-wild-type and the therapy with anti-EGFR (epidermal growth factor receptor) monoclonal antibody cetuximab could be initiated. In the second case, the mutational profile of a patient with initial wild-type RAS-status was continually tracked during the course of treatment. An acquired KRAS exon 3 mutation was detected. The number of KRAS mutated fragments decreased continuously after the discontinuation of the therapy with EGFR-specific antibodies. Conclusion. Liquid biopsy provides a rapid genotype result, which accurately reproduces the current mutation status of tumor tissue. Furthermore, liquid biopsy enables close monitoring of the onset of secondary resistance to anti-EGFR therapy.