Case Studies

CellSearch® Circulating Tumor Cell (CTC) Test

Metastatic Colorectal Cancer (MCRC)

Key Benefit of Using the CellSearch™ CTC Test

  • Reduction in circulating tumor cell count provided confidence that the patient could be moved to a less intensive chemotherapy regimen following the development of neuropathy.

Case Study

Patient Information

  • Age:
  • Diagnosis:
Metastatic Colorectal Cancer (MCRC)
  • Line of Therapy:
  • Current Therapy:
  • Time with Metastasis:
Newly diagnosed
  • CEA*:
  • Sites of Metastasis:
Liver (>10 mets)

* CEA ─ carcinoembryonic antigen

Case Study Snapshot

  • Newly diagnosed metastatic colorectal cancer with baseline elevated CEA of 12 and CTC count of 7 CTC/7.5 mL of blood.
  • CTC levels of 2 and 0 following 2 and 8 cycles of chemotherapy, respectively provided confidence the patient was on an effective line of therapy.
  • CTC counts remaining low, when they had previously been elevated, provided reassurance in the decision to continue a less intensive chemotherapy regimen when the patient developed Grade 2 neuropathy.

Patient Longitudinal Graphs

Patient Longitudinal Graphs

Patient Longitudinal Graphs

Background on the Patient

August T. initially presented with anemia.  Evaluation with colonoscopy revealed a descending colon mass and biopsy confirmed adenocarcinoma of the colon.  The patient subsequently had a CT scan, which revealed the presence of multiple liver metastases.

At baseline before treatment, which was January 2007, the patient had a CEA of 12 and a CTC measurement of 7 CTCs in 7.5mls of blood.  The patient began FOLFOX and beacizumab and tolerated his first 2 treatments quite well.  In February, after 2 doses of therapy, the CEA dropped to 10 and the CTC count decreased to 2.  Encouraged by these test results 6 additional cycles of therapy were given prior to obtaining a repeat CT scan.  This CT scan revealed a significant decrease in both size and number of liver metastases.  An additional CTC count obtained revealed 0 CTCs for 7.5mls of blood.  Since CEA at baseline and immediately following initiation of treatment was only modestly elevated it was not felt that continued ordering would not be particularly helpful.

FOLFOX and beacizumab were continued for a total of 6 months following which time repeat imaging revealed stable liver metastases.  Subsequently, the patient developed Grade 2 neuropathy. Reassured by the initial decrease in CTCs it was decided to drop the oxaliplatin and continue 5-FU and bevacizumab.  After 4 months of therapy the CTC count increased to 5 triggering a repeat CT scan which revealed increasing liver metastases.  As the patient’s neuropathy had improved oxalipatin therapy was reinitiated.  As before, the circulating tumor cells decreased over time however, by March 2008 the patient’s neuropathy worsened and oxaliplatin had to be permanently discontinued.  After 3 additional months of serial CTC measurement the count increased to 8 and a CT scan confirmed liver metastasis progression thus necessitating consideration of alternative therapy.

How CTC were Valuable in the Treatment of this MCRC Patient

Circulating tumor cells were used for informed decision making throughout the course of this patient’s treatment.  An initially elevated CTC count with subsequent decrease after initiation of therapy provided confidence to switch the patient to a less intense chemotherapy regimen following the development of neurotoxicity. Subsequent monitoring of this patient by circulating tumor cell analysis showed progression necessitating consideration of alternative therapy.

For in vitro Diagnostic Use

The CellSearch™ Circulating Tumor Cell Kit is intended for the enumeration of circulating tumor cells (CTC) of epithelial origin (CD45-, EpCAM+, and cytokeratins 8, 18+, and/or 19+) in whole blood.

The presence of CTC in the peripheral blood, as detected by the CellSearch™ Circulating Tumor Cell Kit, is associated with decreased progression-free survival and decreased overall survival in patients treated for metastatic breast, colorectal or prostate cancer.

For further information on intended use, warnings, and limitations, please refer to the CellSearch™ CTC Test Instructions for Use, or visit

CellSearch™ results should be used in conjunction with all clinical information derived from diagnostic test (e.g., imaging or laboratory tests), physical examination and complete medical history, in accordance with appropriate management procedures.

This case study is for educational purposes only and does not constitute professional medical advice. The information provided in this case study should not be relied upon as the basis for making patient management decisions. This case study is not intended to show that any line of therapy is any more or less effective than any other or no therapy.