Circulating Tumor Cells: Beyond Isolation and Detection

*Corresponding author: Michelle J. McNamara*

Abstract

Circulating tumor cells (CTCs) are the precursors to metastases and increased numbers of CTCs in the peripheral circulation have been shown to correlate with decreased progression-free and overall survival. Although the current clinical utility has been focused on the prognostic significance, other clinical applications are being explored, such as determining if a patient is a candidate for treatment, determining the efficacy of treatment, evaluation for resistance to therapy, prediction of metastatic site, or as an early predictor of metastases. Current methodologies are based on quantifying CTCs and include technologies based on physical, immunological, and molecular techniques. However, these have limitations, of which most of them do not have the ability to perform morphological evaluation. Using morphological evaluation, CTCs in body fluids could be used for primary diagnosis in the setting of cancer of unknown primary (CUP) or in initial or early diagnostic scenarios. Additionally, cytological specimens have been shown to be useful for ancillary testing in patients when surgical resection specimens or biopsies are not available. Evaluation of CTCs should incorporate histological, immunehistochemical, and molecular characterization to enable clinicians to obtain the comprehensive diagnostic, prognostic and therapeutic information necessary to provide appropriate personalized care to cancer patients.

Keywords

Circulating tumor cell (CTC); Circulating; Tumor cell; Cancer; Isolation; Detection; Metastasis; Prognosis.

Abbreviations

CTC: Circulating tumor cell; RT-PCR: Reverse transcriptase-polymerase chain reaction; EMT: Epithelial-mesenchymal transition; MET: Mesenchymal-epithelial transition; TRAIL: Tumor necrosis factor-related apoptosis-inducing ligand; CEA: Carcinoembryonic antigen; CUP: Cancer of unknown primary; CAP: College of American Pathologists; AMP: Association for Molecular Pathology; ASCO: American Society of Clinical Oncology.