Simultaneous in situ detection of protein expression of multiple tumor markers of circulating tumor cells and heteroploid of chromosome 8 in primary lung cancer

BACKGROUND: Previously published studies have shown that circulating tumor cells (CTC) play an important role in clinical staging, efficacy monitoring and prognostic evaluation of lung cancer. The aim of the present study was to investigate the significance of simultaneous in situ detection of multiple tumor marker protein expression and chromosome 8 aneuploid of CTC in the diagnosis and treatment of primary lung cancer. METHODS: We investigated the expression of cytokeratin 18 (CK18) and Vimentin on the surface of CTC and the aneuploidy of chromosome 8 in the peripheral blood of 24 patients with metastatic primary lung cancer, which were detected by subtraction enrichment (SE) and immunofluorescence in situ hybridization (iFISH). Their correlation with clinicopathological features, curative effect, and prognosis was analyzed. RESULTS: The positive rate of CTC was 95.83% (23/24). There was a certain correlation between the positive rate of CTC and smoking, and a correlation between the number of CTC and histopathological type. The number of monoploid, diploid, triploid, and polyploid CTC had no statistical correlation with progression-free survival (PFS) or overall survival (OS). However, a tetraploid CTC count of ≥2 was an unfavorable predictor of response; a tetraploid CTC count ≥1 was an unfavorable prognostic predictor of poor OS. The rate of CK18+ CTC in all 24 patients was 4.35% (1/23). Seven out of these 24 patients were also tested for Vimentin, and the rate of Vimentin+ CTC was 85.71% (6/7). Small-cell (≤5 µm) CTC was found in 6 of these 7 patients and accounted for 11.83% (11/93) of the total CTC. The tumor marker phenotype of small-cell CTC was CK18– and Vimentin+. In addition, circulating tumor microthrombi (CTM) were found in 2 of these 7 patients (28.57%). CONCLUSIONS: SE-iFISH has a high detection rate of CTC in the peripheral blood of patients with metastatic primary lung cancer, and it can identify small cell CTC. Tetraploid CTC count ≥2 can predict poor PFS in patients with advanced lung cancer. Tetraploid CTC count ≥1 could predict poor OS in patients with advanced lung cancer. CTM can predict poor prognosis in patients with lung cancer.