Nasopharyngeal carcinoma (NPC) has remarkable epidemiological features, including regional, racial, and familial aggregations. The aim of this review is to describe the epidemiological characteristics of NPC and to propose possible causes for the high incidence patterns in southern China. Since the etiology of NPC is not completely understood, approaches to primary prevention of NPC remain under consideration. This situation highlights the need to conduct secondary prevention, including improving rates of early detection, early diagnosis, and early treatment in NPC patients. Since the 1970's, high-risk populations in southern China have been screened extensively for early detection of NPC using anti–Epstein-Barr virus (EBV) serum biomarkers. This review summarizes several large screening studies that have been conducted in the high-incidence areas of China. Screening markers, high-risk age range for screening, time intervals for blood re-examination, and the effectiveness of these screening studies will be discussed. Conduction of prospective randomized controlled screening trials in southern China can be expected to maximize the cost-effectiveness of early NPC detection screening.

The frequency of nasopharyngeal carcinoma is nearly 100-fold higher in southern Chinese than in most European populations. Earlier studies have suggested that an increased risk of nasopharyngeal carcinoma is associated with specific haplotypes in the HLA region: relative risks slightly over twofold were found for haplotypes A2, Bw46 and the antigen B17. We now report a linkage study based on affected sib pairs which suggests that a gene closely linked to the HLA locus confers a greatly increased risk of nasopharyngeal carcinoma. The maximum likelihood estimate is of a relative risk of approximately 21. The relationship between this suspected disease susceptibility gene (or genes) and known viral and environmental aetiological factors remains to be elucidated.

A total of 363 cases of nasopharyngeal carcinoma (NPC) in Singapore were classified into squamous cell carcinoma (SCC; 73 cases), non-keratinizing carcinoma (NKC; 178 cases) and undifferentiated carcinoma (UC; 172 cases). Possible biological differences between these histologic types and between tumors with and without lymphocytic infiltration were investigated by correlations with survival rates and with selected epidemiologic, immunovirologic, and immunogenetic data on the disease. The 5-year survival rates following radiotherapy were 25.3% for all cases and 58.8% for tumors restricted to the nasopharynx. The 5-year survival rate for SCC was poorer than for the combined NKC and UC groups (p < 0.05). The 3-year survival rate was better for tumors with lymphocytic infiltration (p < 0.05), but there were no differences in the 5-year survivals. The survival rates were better in females (p < 0.01) and in the younger age groups (p < 0.01). There were no significant correlations between histopathology of NPC and the distributions of cases by age, sex, HLA antigen profiles, or cell-mediated immune status. Spuamous cell carcinoma was associated with lower levels of antibodies to the Epstein-Barr nuclear antigen (p < 0.05), but there were no differences with respect to antibodies against other EBV related antigens. These findings support the view that SCC, NKC, and UC of the nasopharynx, as defined in the WHO classification, are variants of a fairly homogeneous group of neoplasms in the Singapore population.

This paper reports the results of 8 years of HLA typing of newly diagnosed nasopharyngeal carcinoma (NPC) patients among Chinese in Singapore, and compares the HLA profile of NPC cases with that of the normal Chinese population. Earlier results had indicated an association with A2 and BW46, but the heterogeneity of the earlier case series, which contained a proportion of long-term survivors, obscured other aspects of the relationship. In this paper, the risk associated with A2 (relative risk = 1.5) and BW46 (relative risk = 1.9) is confirmed, showing a much higher relative risk in the presence of both antigens, and a risk is also demonstrated for B17 (relative risk = 2.1). Relative risks of less than unity are observed for AII (relative risk = 0.5) and B13 (relative risk = 0.5). Data from family studies indicate the importance of the haplotype A2.BW46 in determining risk for NPC.

This paper reports the results of two studies which compared the HL-A profile of predominantly Chinese patients with nasopharyngeal carcinoma to that of suitably chosen controls. The first study demonstrated a significant increase in the proportion of NPCpatients in whom less than two second locus antigens were detectable. The second confirmatory study also demonstrated the same phenomenon at a high level of statisticul significance, and furthermore showed a significant elevation among the NPC patients of the frequency of HL-A2. Both the elevution of the H L A 2 frequency and the deficit of detectable second locus antigens remained significant after application of the most conservhtive correction factor for the number of antigens investigated. Various sources of bias have been considered and appear not to have appreciably influenced the results. The results are discussed in terms of the postulated genetic basis of the elevated risk for NPC among the Chinese.

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