Clinical Services

CellSearch® Circulating Tumor Cell Test

Metastatic cancer occurs when cancer spreads from its primary site to other places in the body through the circulatory system or the lymphatic system. In the circulatory system, metastasis may begin via circulating tumor cells (CTCs) - cancer cells that spread through the blood after detaching from a solid tumor and entering the bloodstream.

Circulating tumor cells, which are extremely rare in individuals without malignancy, are present at a wide range of frequencies in patients with various metastatic carcinomas.1 The assessment of CTCs may assist clinicians in monitoring and predicting cancer progression and in evaluating response to therapy in patients with metastatic cancer.2-3 In particular, clinical studies have focused on metastatic breast,4-6 colorectal,7-8 and prostate9 cancer.

CellSearch® CTC Test and its Role in the Management of Metastatic Cancer

Traditionally, the progression of metastatic cancer is determined through laboratory studies using tumor markers or imaging studies, such as a CT scan. Another, newer method for monitoring metastatic cancer is the CellSearch® Circulating Tumor Cell (CTC) test.

The CellSearch® Circulating Tumor Cell (CTC) test is a simple blood test that captures, identifies, and counts the number of CTCs in a blood sample to predict progression free survival (PFS) and overall survival (OS) in patients with metastatic breast, colorectal and prostate cancer. Results of serial testing for CTCs, in conjunction with other clinical methods for disease monitoring, can help clinicians assess progression, guiding more informed care decisions earlier.

Unlike other methods of monitoring metastatic cancer, the CTC test counts the number of cancer cells that have broken away from the tumor and are currently circulating in the blood stream. Clinical studies have shown that detection of these cells can predict disease progression and survival in patients with metastatic cancer.

A CTC test can be performed prior to beginning therapy, and then as early as 2-5 weeks after therapy initiation. In addition, CTC testing can be used at any time along the continuum of care. This flexibility allows doctors to optimize patient care strategies.

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Usage of the CellSearch® CTC Test in Clinical Practice

The CTC test identifies and counts the number of CTCs in whole blood—detecting as few as one CTC in 7.5 mL of blood.

Using a predetermined cutoff number—5 CTCs for metastatic breast and prostate cancer; 3 CTCs for metastatic colorectal cancer—the test can predict whether a patient’s survival is favorable or less favorable. Clinical studies have shown that:

  1. If the number of CTCs is below the cutoff, indications are that the prognosis is favorable.
  2. If the number of CTCs in a sample is above the cutoff, indications are that the disease may be progressing.

Although not intended to replace imaging, CellSearch® results may supplement imaging in the assessment of disease progression in patients with metastatic breast10 or colorectal cancer.8  Furthermore, in patients with metastatic breast cancer, the number of CTCs may predict treatment response earlier than imaging (3–4 weeks vs. 8–12 weeks after initiation of therapy).5,10  Similarly, in patients with metastatic prostate cancer, CTC counts were earlier predictors of treatment response than reduction in prostate-specific antigen (PSA) levels, which are commonly used to evaluate disease progression (2–5 weeks vs. 6–8 weeks).9


Please contact BioVantra Client Support Center at (866) 627-8221 to arrange for CTC testing. Our experienced Client Support Team can assist with:

  • Specialized Testing Requisition
  • Sample requirements
  • Logistics and specimen transportation
  • Testing methodology
  • Report delivery, status or interpretation
  • Expert oncology and pathology consultations
  • Requests for BioVantra literature and scientific references

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  1. Allard WJ, Matera J, Miller MC, Repollet M, Connelly MC, Rao C, Tibbe AG, Uhr JW and Terstappen LW: Tumor cells circulate in the peripheral blood of all major carcinomas but not in healthy subjects or patients with nonmalignant diseases. Clin Cancer Res. 10: 6897-904, 2004.
  2. Beerepoot LV, Mehra N, Vermaat JS, Zonnenberg BA, Gebbink MF and Voest EE: Increased levels of viable circulating endothelial cells are an indicator of progressive disease in cancer patients. Ann Oncol. 15: 139-45, 2004.
  3. Cohen SJ, Alpaugh RK, Gross S, O'Hara SM, Smirnov DA, Terstappen LW, Allard WJ, Bilbee M, Cheng JD, Hoffman JP et al.: Isolation and characterization of circulating tumor cells in patients with metastatic colorectal cancer. Clin Colorectal Cancer. 6: 125-32, 2006.
  4. Gaforio JJ, Serrano MJ, Sanchez-Rovira P, Sirvent A, Delgado-Rodriguez M, Campos M, de la Torre N, Algarra I, Duenas R and Lozano A: Detection of breast cancer cells in the peripheral blood is positively correlated with estrogen-receptor status and predicts for poor prognosis. Int J Cancer. 107: 984-90, 2003.
  5. Cristofanilli M, Budd GT, Ellis MJ, Stopeck A, Matera J, Miller MC, Reuben JM, Doyle GV, Allard WJ, Terstappen LW et al.: Circulating tumor cells, disease progression, and survival in metastatic breast cancer. N Engl J Med. 351: 781-91, 2004.
  6. Cristofanilli M: Circulating tumor cells, disease progression, and survival in metastatic breast cancer. Semin Oncol. 33: S9-14, 2006.
  7. Sastre J, Maestro ML, Puente J, Veganzones S, Alfonso R, Rafael S, Garcia-Saenz JA, Vidaurreta M, Martin M, Arroyo M et al.: Circulating tumor cells in colorectal cancer: correlation with clinical and pathological variables. Ann Oncol. 19: 935-8, 2008.
  8. Cohen SJ, Punt CJ, Iannotti N, Saidman BH, Sabbath KD, Gabrail NY, Picus J, Morse M, Mitchell E, Miller MC et al.: Relationship of circulating tumor cells to tumor response, progression-free survival, and overall survival in patients with metastatic colorectal cancer. J Clin Oncol. 26: 3213-21, 2008.
  9. de Bono JS, Scher HI, Montgomery RB, Parker C, Miller MC, Tissing H, Doyle GV, Terstappen LW, Pienta KJ and Raghavan D: Circulating tumor cells predict survival benefit from treatment in metastatic castration-resistant prostate cancer. Clin Cancer Res. 14: 6302-9, 2008.
  10. Budd GT, Cristofanilli M, Ellis MJ, Stopeck A, Borden E, Miller MC, Matera J, Repollet M, Doyle GV, Terstappen LW et al.: Circulating tumor cells versus imaging--predicting overall survival in metastatic breast cancer. Clin Cancer Res. 12: 6403-9, 2006.

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