Circulating tumor cells: clinical validity and utility

Int J Clin Oncol. 2017 Jun;22(3):421-430. doi: 10.1007/s10147-017-1105-2. Epub 2017 Feb 25.


Circulating tumor cells (CTCs) are rare tumor cells and have been investigated as diagnostic, prognostic and predictive biomarkers in many types of cancer. Although CTCs are not currently used in clinical practice, CTC studies have accumulated a high level of clinical validity, especially in breast, lung, prostate and colorectal cancers. In this review, we present an overview of the current clinical validity of CTCs in metastatic and non-metastatic disease, and the main concepts and studies investigating the clinical utility of CTCs. In particular, this review will focus on breast, lung, colorectal and prostate cancer. Three major topics concerning the clinical utility of CTC are discussed-(1) treatment based on CTCs used as liquid biopsy, (2) treatment based on CTC count or CTC variations, and (3) treatment based on CTC biomarker expression. A summary of published or ongoing phase II and III trials is also presented.

Keywords: Biomarkers; Circulating tumor cells; Clinical trials; Clinical utility; Clinical validity.

Publication types

  • Review

MeSH terms

  • Biomarkers, Tumor / metabolism
  • Biopsy
  • Breast Neoplasms / pathology
  • Colorectal Neoplasms / pathology
  • Female
  • Humans
  • Lung Neoplasms / pathology
  • Male
  • Neoplasms / mortality
  • Neoplasms / pathology*
  • Neoplasms / therapy
  • Neoplastic Cells, Circulating / metabolism
  • Neoplastic Cells, Circulating / pathology*
  • Pathology, Clinical / methods
  • Prognosis
  • Prostatic Neoplasms / pathology


  • Biomarkers, Tumor