RESUMEN
<p><b>BACKGROUND</b>To understand the significance of detection of serum sialic acid (SA) and Epstein-Barr virus VCA-IgA (EBV-CA-IgA) in diagnosis and monitoring radiotherapy effectiveness of nasopharyngeal carcinoma (NPC) patients.</p><p><b>METHODS</b>Serum SA and EBV-CA-IgA were detected in 65 cases with NPC before radiotherapy and one months after radiotherapy and 21 cases one year after radiotherapy for NPC with local recurrence and/or distant metastasis. Healthy persons and patients with benign lesions of head and neck were also enrolled as control group.</p><p><b>RESULTS</b>SA and EBV-CA-IgA of NPC patients before radiotherapy were significantly higher than those in control group (P<0.01). The sensitivity of combination of SA and EBV-CA-IgA (96.9%) was higher than those determined alone (P<0.05). The SA level of NPC patients after radiotherapy and without recurrence after radiotherapy was reduced significantly compared to the NPC patients before radiotherapy (P<0.01). The SA level of NPC patients with recurrence was significantly higher than that in NPC patients without recurrence (P<0.01), whereas the positive rate of EBV-CA-IgA changed little.</p><p><b>CONCLUSION</b>Dynamic detection of serum SA may be a valuable technique for diagnosis and monitoring radiotherapy effectiveness in NPC patients. The combined determination of the two indexes can raise the positive rate of patients with NPC.</p>