The Epidemiology of nasopharyngeal carcinoma

dc.contributor.author	Khoon Chan, Chee M.S.
dc.date.accessioned	2015-10-13T04:37:55Z
dc.date.available	2015-10-13T04:37:55Z
dc.date.issued	1990-12
dc.description.abstract	Nasopharyngeal carcinoma (NPC) patients have elevated IgG and IgA antibody titers against the Epstein-Barr viral capsid antigen (VCA) and the diffuse component of the early antigen complex (EA-D) at diagnosis. Several studies have implied that the presence of anti-VCA-lgA can be used as a screening marker for early NPC. To evaluate this further, we undertook a serologic case-control study based on four serum banks which together had specimens from over 240,000 persons. Seven cases of undifferentiated or poorly differentiated NPC were diagnosed in the period after serum collection ranging from 26 months to 154 months. Two controls per case matched on serum bank, age, sex, race, and date of serum collection were selected by a pre-determined random process. For anti-VCA-IgG, the geometric mean titer for cases (88.3) was significantly higher than that for controls (75.5) (p < 0.05). The difference was greatest among the Asian patients. No significant differences were found for anti-VCA-IgA, anti-EA-D, anti-EA-R or antiEBNA. No time effects were evident when titers were plotted against time of blood collection preceding diagnosis. Our results do not suggest EBV activation in the period preceding NPC diagnosis, nor that detectable IgA antibody against VCA is a marker for early disease. key words Nasopharyngeal carcinoma, Epstein-Barr virus, serological screening The Epstein-Barr virus (EBV) has been consistently associated with the occurrence of undifferentiated and poorly differentiated nasopharyngeal carcinoma (NPC). NPC patients from around the world, at or following diagnosis, often have high IgG titers against the viral capsid antigen (VCA) and the diffuse component of the EBV early antigen complex (EA-D) but not the restricted (EA-R) (de Schryver et al., 1969, 1974; Henle, w. et al., 1970, 1973; Lin et al., 1971; Henderson et al., 1974). In contrast, patients with carcinomas of the oropharynx or hypopharynx or tumors of the nasopharynx other than carcinomas usually have much lower titers. IgA titers against the VCA and the EA-D are also markedly elevated in the sera and saliva of NPC patients (Wara et al., 1975; Henle, G. et al., 1977). Elevated titers against an EBV-specific DNase has also been reported (Cheng et al., 1980). Nucleic acid hybridization consistently demonstrated the presence of EBV-DNA in NPC biopsies (zur Hausen et al., 1970, 1974; Nonoyama et al., 1973), and specifically in the anaplastic or poorly differentiated carcinoma cells (Wolf et al., 1973, 1975; Desgranges et al., 1975). Biopsies from carcinomas at other sites of the head and neck and from other types of tumors of the nasopharynx have been mostly negative for EBV-DNA (Andersson-Anvret et al., 1977). The EBV-associated nuclear 5 antigen (EBNA) is also detected in anaplastic NPC cells, but not in the lymphoid elements of the tumor (Wolf et al., 1973, 1975; Huang et al., 1974; Klein et al., 1974; Desgranges et al., 1975). These findings have prompted much interest in the potential of EBV serologic markers -- in particular IgA antibodies against VCA -- as screening aids in early detection of NPC (Zeng, 1985). The data on EBV serology prior to diagnosis is sparse, and the temporal relationship between altered EBV serological profile and emergence of disease remains obscure. One clinical report, and three other studies have yielded conflicting results (Ho et al., 1978; Lanier et al., 1980; Zeng et al., 1985; Chen et al., 1985). The purpose of this study is to evaluate the pattern of pre-diagnosis EBV antibodies in a series of NPC patients.	en_US
dc.identifier.uri	http://hdl.handle.net/123456789/1298
dc.language.iso	en	en_US
dc.subject	Nasopharyngeal carcinoma	en_US
dc.subject	Epstein-Barr virus	en_US
dc.subject	Serological screening	en_US
dc.title	The Epidemiology of nasopharyngeal carcinoma	en_US
dc.type	Thesis	en_US