Interpretive Handbook

Test 89089 :
Circulating Tumor Cells (CTC) for Breast Cancer by CellSearch, Blood

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

In patients with metastatic cancer, tumor cells may be present in the bloodstream (circulating tumor cells: CTCs). Studies suggest that the number of CTCs is associated with progression-free and overall survival in patients with metastatic breast cancer.(1,2) Serial testing for CTCs, in conjunction with other clinical methods for monitoring breast cancer, can assist physicians in the management of these patients.(3)

Useful For Suggests clinical disorders or settings where the test may be helpful

Aids in monitoring patients with metastatic breast cancer

Interpretation Provides information to assist in interpretation of the test results

Results are reported as favorable or unfavorable. In patients with metastatic breast cancer, unfavorable results (> or =5 circulating tumor cells/7.5 mL of blood) are predictive of shorter progression-free survival and shorter overall survival.(1)

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

This test is FDA approved for use only in patients with metastatic breast cancer; it is not approved for patients with nonmetastatic breast cancer.


The CellSearch System is FDA approved for colon and prostate cancer.

-For colon cancer patients, order CTCCC / Circulating Tumor Cells (CTC) for Colon Cancer by CellSearch, Blood.

-For prostate cancer patients, order CTCPC / Circulating Tumor Cells (CTC) for Prostate Cancer by CellSearch, Blood.


This test does not predict whether patients with unfavorable results will have better clinical outcomes if they are switched to alternative treatment regimens. It does not provide information about the primary site of a tumor.


Patients on doxorubicin (Adriamycin) must wait a minimum of 7 days after administration before blood is drawn for this test.


Blood specimens must be drawn in a CellSave tube and received in the laboratory for processing within 96 hours of the blood draw.


Interfering substances may cause the ferrofluid reagent to aggregate, which may compromise results. The analysis process may not be able to detect all CTCs in the sample.

Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

An interpretive report will be provided.

Clinical References Provides recommendations for further in-depth reading of a clinical nature

1. Cristofanilli M, Budd GT, Ellis MJ, et al: Circulating tumor cells, disease progression, and survival in metastatic breast cancer. N Engl J Med 2004;351:781-791

2. Allard WJ, Matera J, Miller MC, et al: Tumor cells circulate in the peripheral blood of all major carcinomas but not in healthy subjects or patients with nonmalignant diseases. Clin Cancer Res 2004 Oct 15;10:6897-6904

3. Cristofanilli M, Hayes DF, Budd GT, et al: Circulating tumor cells: a novel prognostic factor for newly diagnosed metastatic breast cancer. J Clin Oncol 2006 Mar 1;23:1420-1430