Use of magnetic enrichment for detection of carcinoma cells in fluid specimens

BACKGROUND Ascites fluid or a pleural effusion are common events in metastatic carcinoma, but they also can be associated with several other medical conditions. The standard for determination of malignancy in these situations is cytologic evaluation of these fluids. Although this method is frequently successful, there are times when it fails, even when the patient has a malignancy, either because of insufficient cells in the fluid or for other reasons. This study addresses this problem taking advantage of the recent advances in technology for detection of rare epithelial cells in liquid specimens. METHODS The authors examined fluid specimens from 59 patients to determine the frequency of recovery of epithelial cells compared with that achieved by conventional cytopathology. The Dynal CELLection Epithelial Enrich (Dynal AS, Oslo, Norway) method was used. This method is based on immunomagnetic selection of cells binding to EpCAM antibodies. Carcinoma cells were confirmed by morphology and, when there was sufficient material, by E‐cadherin staining. RESULTS Grouping the cases by cytologic diagnosis, the authors found malignant cells using the cell enrichment assay in 11 of 12 malignant cases, 2 of 5 atypical cases, and 3 of 42 negative cases. Further investigations were conducted on the five cases that were cytologically negative or atypical but yielded epithelial cells after immunomagnetic enrichment. Four cases ultimately were proven malignant by other methods and one had incomplete follow‐up. CONCLUSIONS The new methods available for epithelial cell enrichment in liquids may be used successfully on cytologic fluid specimens and may lead to increased sensitivity for detection of malignancy, and consequently more accurate staging. Cancer 2002;94:205–11. © 2002 American Cancer Society. Immunomagnetic epithelial cell enrichment can find tumor cells in pleural and peritoneal fluids that would not be detected by conventional cytologic analysis.