Immunocytochemical detection of circulating esophageal carcinoma cells by immunomagnetic separation.

Background: Recent developments in detection of micrometastasis have revealed a considerable incidence of systemic disease in patients who would previously have been diagnosed as having solid tumours only. The purpose of this study was to investigate the prevalence and clinical significance of circulating carcinoma cells in patients with esophageal squamous cell carcinoma (ESCC).
Materials and Methods: Peripheral blood samples from 47 primary ESCC patients were enriched by immunomagnetic separation (IMS) using Ber-EP4-conjugated beads (Dynabeads anti-epithelial cell) and immunostained with an anti-cytokeratin (anti-CK) antibody. We assayed samples from 12 patients to compare the detection of CK-reactive cells using IMS with the detection of CK 19 mRNA using a reverse transcriptase-polymerase chain reaction (RT-PCR) method.
Results: CK-reactive cells were observed in 18 out of 47 patients (38%). The detection rate was closely correlated with the stage of disease (TNM stage) (p = 0.0017). In 33 patients who underwent esophagectomy, 4 out of 7 patients (57%) positive for CK cells and only 2 out of 26 patients (7.7%) negative suffered from recurrence in the distant lymph nodes or lungs (p = 0.0108). When IMS and RT-PCR were compared, all 3 samples that were CK-positive by IMS had CK 19 mRNA detected by RT-PCR. However, the other 4 samples with CK 19 mRNA by RT-PCR were negative for CK cells by IMS. Of 7 patients positive for CK-reactive cells before chemotherapy or chemoradiotherapy, 4 patients negative after treatment survived but 3 patients who remained positive died within 6 months.
Conclusion: Immunocytochemical detection of circulating carcinoma cells by IMS may be a specific method for the diagnosis of systemic disease and for monitoring treatment response.