RESUMEN
<p><b>OBJECTIVE</b>To explore the clinical significance of cytokeratin 19 fragments test in the diagnosis of nasopharyngeal carcinoma.</p><p><b>METHODS</b>The study included 102 cases of nasopharyngeal carcinoma, 90 cases of nasal polyp/nasopharyngitis, and 150 healthy individuals. RT-PCR was used to detect CK19 mRNA expression and Western blot to detect CK19 fragment protein expression in tissues of nasopharyngeal carcinoma. Expression of CK19-2G2 was examined by immunohistochemistry. Chemiluminescence analysis was used to detect the serum levels of CK19-2G2, and ELISA to detect that of EB-VCA IgA.</p><p><b>RESULTS</b>Among 102 cases of nasophryngeal carcinoma, 64 showed CK19 mRNA expression by RT-PCR, 60 showed CK19 protein fragments in tumor tissues by Western blot, and 66 showed expression of CK19-2G2 by immunohistochemistry in nasopharyngeal carcinoma, including strong positivity in 20 cases, moderate in 34 cases and weak in 12 cases. The sensitivity and specificity of CK19-2G2 in the diagnosis of nasopharyngeal carcinoma were 49.0% and 89.2%, and those of EB-VCA IgA were 52.9% and 85.4%, respectively. The combined detection of CK19-2G2 and EB-VCA IgA increased the sensitivity to 73.5% while the specificity remained at 80.0%.</p><p><b>CONCLUSIONS</b>High levels of CK19-2G2 fragment expressed in tissue and serum are present in patients with nasopharyngeal carcinoma. The serum level of CK19-2G2 is helpful in the diagnosis of nasopharyngeal carcinoma. Furthermore, the combination of serum CK19-2G2 and EB-VCA IgA improves the detection sensitivity.</p>