Background: The pathogenesis of nasopharyngeal carcinoma has been under intense investigation, especially of its peculiar predominance in southern China. The authors previously reported consistent loss of genetic material on the short arm of chromosome 3 in a few nasopharyngeal carcinoma cases. In this study, the authors examined the genetic changes as well as the presence of Epstein-Barr virus (EBV) genome on 36 nasopharyngeal carcinoma primary biopsy specimens of the undifferentiated type and the correlation of the findings to patients' clinical status.
Methods: The authors examined the DNA from tumor tissue and from matched blood leukocytes of 36 patients who suffered from nasopharyngeal carcinoma by the restriction fragment length polymorphism analysis. The genotyping for EBV was carried out by polymerase chain reaction using primers complementary to both types of EBV and probes specific to EBNA-2A (EBV-A) or EBNA-2B (EBV-B).
Results: A consistent deletion at two specific locus of the short arm of chromosome 3 was observed in all informative cases. The authors also found that EBV genome, especially type A, was present in 35 of 36 cases. In the remaining one case, EBV-B was detected.
Conclusions: As the same tumor tissue was used for both genetic and viral studies in each case, the results may represent sequential genetic lesions in the pathogenesis and/or summation of genetic events. Moreover, 7 of 32 informative tumors were from patients of early staging (Stages I and II), which suggests the genetic changes may occur in the early development of nasopharyngeal carcinoma. Difference in allele frequency in specific locus was also noted between Asian and white patients for the first time.