TY - JOUR
T1 - External quality assurance of circulating tumor cell enumeration using the CellSearch® system
T2 - A feasibility study
AU - Kraan, Jaco
AU - Sleijfer, Stefan
AU - Strijbos, Michiel H.
AU - Ignatiadis, Michail
AU - Peeters, Dieter
AU - Pierga, Jean Yves
AU - Farace, Francoise
AU - Riethdorf, Sabine
AU - Fehm, Tanja
AU - Zorzino, Laura
AU - Tibbe, Arjan G.J.
AU - Maestro, Marisa
AU - Gisbert-Criado, Rafael
AU - Denton, Graeme
AU - De Bono, Johann S.
AU - Dive, Caroline
AU - Foekens, John A.
AU - Gratama, Jan W.
PY - 2011/1/1
Y1 - 2011/1/1
N2 - Background: Circulating tumor cells (CTCs) are cells that have detached from solid tumors and entered the blood. CTCs can be detected, among others, by semi-automated immunomagnetic enrichment and image cytometry using CellSearch® (Veridex, Raritan, NJ). We studied the feasibility of external quality assurance (EQA) of the entire CellSearch procedure from blood draw to interpretation of results in multiple laboratories. Methods: Blood samples from six cancer patients and controls were distributed to 14 independent laboratories to test between-laboratory, between-assay, and between-instrument variation. Additionally, between-operator variability was assessed through the interpretation of blinded images of all blood samples on a website. Results: Shipment and storage of samples had no influence on CTC values. Between-instrument (coefficient of variation (CV) < 12%) and between-assay variation was low (CV ≤ 20%), indicating high reproducibility. However, between-laboratory CV ranged from 45 to 64%. Although inter-operator agreement on image interpretation (Fleiss' I° statistics) ranged from " to "almost perfect," image interpretation, particularly of samples containing high numbers of apoptotic cells, was the main contributor to between-laboratory variation. Conclusions: This multicenter study shows the feasibility of an EQA program for CTC detection in patient samples, and the importance of continuation of such a program for the harmonization of CTC enumeration.
AB - Background: Circulating tumor cells (CTCs) are cells that have detached from solid tumors and entered the blood. CTCs can be detected, among others, by semi-automated immunomagnetic enrichment and image cytometry using CellSearch® (Veridex, Raritan, NJ). We studied the feasibility of external quality assurance (EQA) of the entire CellSearch procedure from blood draw to interpretation of results in multiple laboratories. Methods: Blood samples from six cancer patients and controls were distributed to 14 independent laboratories to test between-laboratory, between-assay, and between-instrument variation. Additionally, between-operator variability was assessed through the interpretation of blinded images of all blood samples on a website. Results: Shipment and storage of samples had no influence on CTC values. Between-instrument (coefficient of variation (CV) < 12%) and between-assay variation was low (CV ≤ 20%), indicating high reproducibility. However, between-laboratory CV ranged from 45 to 64%. Although inter-operator agreement on image interpretation (Fleiss' I° statistics) ranged from " to "almost perfect," image interpretation, particularly of samples containing high numbers of apoptotic cells, was the main contributor to between-laboratory variation. Conclusions: This multicenter study shows the feasibility of an EQA program for CTC detection in patient samples, and the importance of continuation of such a program for the harmonization of CTC enumeration.
KW - circulating tumor cells
KW - external quality assessment
KW - immunomagnetic enrichment
KW - multicenter study
KW - rare events
UR - http://www.scopus.com/inward/record.url?scp=79951909396&partnerID=8YFLogxK
U2 - 10.1002/cyto.b.20573
DO - 10.1002/cyto.b.20573
M3 - Article
C2 - 21337491
AN - SCOPUS:79951909396
SN - 1552-4949
VL - 80 B
SP - 112
EP - 118
JO - Cytometry Part B - Clinical Cytometry
JF - Cytometry Part B - Clinical Cytometry
IS - 2
ER -