Some people think that a positive EBV antibody means they have nasopharyngeal carcinoma, so they think they have nasopharyngeal carcinoma when their blood is positive for EBV antibodies during a routine physical examination, and they become nervous and restless. This situation is often encountered in daily outpatient clinics. To understand the relationship between positive EBV antibodies and nasopharyngeal carcinoma, we must first understand the EBV.
EBV is a widespread human herpesvirus, and is one of the most common viruses that cause colds in humans, and almost everyone has been infected with EBV by the age of 25. In one case, the EBV invades an epithelial cell and divides and multiplies, eventually producing a large number of viruses that rupture and kill the cell. In the other case, the EBV does not divide and multiply, but instead inserts its DNA into the DNA of the epithelial cell, or forms an appendage within the epithelial cell, and remains there for a long time as the epithelial cell divides. The latter condition is called latent infection and is more closely related to the development of nasopharyngeal carcinoma.
The human body produces many antibodies to fight the EBV after infection. Among these antibodies, the EBV capsid antibody (VCA-IgA) is the one that is most used clinically and has the greatest significance in the diagnosis of nasopharyngeal cancer. VCA-IgA is usually present in the blood for several months and then gradually declines until it becomes normal. However, some people may experience a mild but transient increase in VCA-IgA when they are re-infected with EBV. If this antibody remains elevated, one should be alert for the presence of nasopharyngeal carcinoma. We did a cohort study that showed that the incidence of nasopharyngeal cancer was 40 times higher in VCA-IgA-positive people than in VCA-IgA-negative people. Therefore, VCA-IgA testing can be used as an indicator to screen for nasopharyngeal cancer and to identify people at high risk for nasopharyngeal cancer.
VCA-IgA positivity is not unique to nasopharyngeal carcinoma. Patients with infectious mononucleosis are also often positive for this antibody, as are some patients with other head and neck malignancies (e.g., parotid cancer). In contrast, 5-7% of patients diagnosed with nasopharyngeal carcinoma have negative blood tests for VCA-IgA. Therefore, a positive VCA-IgA does not mean that one has nasopharyngeal cancer, and a negative VCA-IgA does not exclude the diagnosis of nasopharyngeal cancer.
Then, what should be done if VCA-IgA positive is found in physical examination? First of all, you should not be too nervous, and then go to a specialized oncology hospital for quantitative testing of VCA-IgA. If VCA-IgA 1:80 and there is no swelling in the nasopharynx and neck, such people should be reviewed regularly. If VCA-IgA≥1:80, besides routine examination of nasopharynx and neck, MRI of nasopharynx and nasopharyngeal electron microscopy should also be done.