Background: Epstein-Barr virus (EBV) is associated with various lymphoproliferative disorders and nasopharyngeal carcinoma. Recently, some gastric cancer cells were observed to contain the EBV sequence. We detected EBV in gastric cancer by using PCR to determine the frequency of EBV-associated gastric cancer, and performed immunohistochemical staining for the latent membrane protein (LMP1), p53 and CD44 to investigate the possible mechanism in EBV-associated gastric cancer.
Methods: Eighty-seven formalin-fixed and paraffin-embedded blocks (40 gastric adenocarcinomas, 34 adjacent normal tissues, 13 metastatic lymph nodes) from 40 surgically resected gastric specimens were studied. All patients were diagnosed with gastric cancer at the Kang-Nam St. Mary's Hospital between April 1995 and April 1997. After DNA was extracted from each paraffin block, we performed PCR and immunohistochemical staining for the LMP1, p53 and CD44.
Results: EBV was detected in 4 of 40 cases (10%). In 1 of 4 EBV-positive cases, EBV was also detected in a metastatic lymph node. The immunohistochemical staining for the LMP1, p53 and CD44 were negative in all the EBV-positive cancer patients. Of the patients having these cancers, 2 had a poorly differentiated adenocarcinoma with a lymphoepithelioma-like morphology.
Discussion: The frequency of EBV-associated gastric cancer is about 10% in Korea. Considering the negative result of the immunohistochemical staining for the LMP1, p53 and CD44, EBV-associated gastric cancer seems to have a different mechanism of tumorigenesis from ordinary gastric cancer or other EBV-associated cancers. This specific mechanism must be determined by further large scale studies.