Prevalence and relevance of EBV latency in nasopharyngeal carcinoma in Israel.
BACKGROUND
Nasopharyngeal carcinoma (NPC) is frequently associated with Epstein-Barr virus (EBV). The incidence of NPC in Western countries is lower than in the Far East, and EBV latency in NPC is less prevalent. Israel, as a part of the Mediterranean area, is one of the countries with an intermediate risk for NPC.


METHODS
Immunohistochemistry (IHC) for latent membrane protein 1 (LMP-1) and in situ hybridisation (ISH) for EBV encoded RNA (EBER) were used to evaluate the prevalence and possible prognostic value of EBV latency among Israeli patients with NPC. Forty five patients with different NPC histologies were studied.


RESULTS
LMP-1 IHC was positive in six samples only, all with undifferentiated histology. EBER ISH was positive in 40 of the 45 samples. According to histological type, three of five patients with squamous cell carcinoma were EBV positive and 37 of 40 non-keratinising and undifferentiated carcinoma cases were positive. Although EBV was more prevalent in patients with non-squamous carcinoma, the difference was not significant, probably because of the small number of patients with keratinising carcinoma. With regard to the clinical categories and survival, no significant difference could be detected between patients who were positive or negative for EBER ISH. No association was found between EBV latency and patient sex, age, origin, stage, or survival.


CONCLUSIONS
NPC in Israel is highly associated with EBV latency as detected by EBER ISH. LMP-1 IHC is considerably less sensitive in detecting EBV latency in NPC among the same patient group.
Bar-Sela
G
G
Department of Oncology, Rambam Medical Centre, PO Box 9602, Haifa 31096, Israel. g_barsela@rambam.health.gov.il
Kuten
A
A
Minkov
I
I
Gov-Ari
E
E
Ben-Izhak
O
O
D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D020031:Epstein-Barr Virus Infections / Q000150:complications / Q000821:virology*; D005260:Female; D004854:Herpesvirus 4, Human / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D017403:In Situ Hybridization / Q000379:methods; D007557:Israel; D008297:Male; D008875:Middle Aged; D009303:Nasopharyngeal Neoplasms / Q000150:complications / Q000821:virology*; D009367:Neoplasm Staging; D012367:RNA, Viral / Q000032:analysis; D014763:Viral Matrix Proteins / Q000032:analysis
C037662:EBV-associated membrane antigen, Epstein-Barr virus; D012367:RNA, Viral; D014763:Viral Matrix Proteins