From 1950 to 1989 one hundred and forty-four cases of either undifferentiated nasopharyngeal carcinoma (NPC) or salivary gland carcinoma (SGC) were diagnosed in Greenlanders, all born in Greenland. The Greenland SGC is an anaplastic carcinoma with histopathology and electronmicroscopic cytopathological alterations as found in undifferentiated NPC. Both NPC and SGC from Greenland and Alaska are associated with Epstein-Barr virus infection. The incidence rate of NPC based on newly diagnosed cases during the last 15 years is 12.7 for men and 9.2 for women. The same figures for anaplastic SGC are 3.4 and 3.1. These are among the highest incidence rates of Epstein-Barr virus associated carcinomas on record. From 1950 to 1989 there has been an increase in the rate of NPC. From the cumulated rate, it can be predicted that the number of cases will continue to increase during the years to come. During the ten year period 1980 to 1989 patients were questioned about their childhood life style and the family history was taken. The Inuit lifestyle is quite different from that of Europeans and Chinese, but in common with Chinese from Guangzhou (formerly Canton) Greenlanders have a high consumption of fish, fresh as well as dried. Familial clustering has been rarely reported, but in the present investigation 27% of the patients diagnosed between 1980 and 1990 had a positive familial history with one or more confirmed cases among first degree relatives.(ABSTRACT TRUNCATED AT 250 WORDS)
There is a high incidence of undifferentiated nasopharyngeal carcinoma (NCP) in certain populations, including Greenland Eskimos. The cancer appears to have a causal association with Epstein-Barr virus (EBV), which is regularly found in NPC epithelial cells. With the aim of developing a method of screening or facilitating early diagnosis of NPC, we used the polymerase chain reaction to examine exfoliated nasopharyngeal cells for EBV in 54 Greenland and 17 white Danish subjects, none of whom was suspected of having NPC. EBV DNA was found in 81% of Greenland and 35% of Danish subjects. These findings support the concept of EBV infection leading in most cases to a chronic carrier state. It is concluded that EBV detection in nasopharyngeal cells is not at present a suitable method for identification of individuals at increased risk of developing NPC.
The Epstein-Barr virus (EBV)-specific antibody profile of 101 Greenland Eskimo children was determined. The proportion of children with serological evidence of recent or past primary EBV infections rose from 22% at 6 months of age to 79% at 24 months of age. All but 2 of 49 children more than 4 years of age proved seropositive. The geometric mean titre (GMT) of antibodies to the viral capsid antigen (VCA) was highest during the first 3 years of life and declined sharply to a lower, nearly constant level in older children. The GMT of antibodies to the nuclear antigen (EBNA), rose slowly during the first 4 years of life to its persistent level. None of the children had a history of illnesses comparable to infectious mononucleosis. The results have shown that in this population with an enhanced risk of nasopharyngeal carcinoma, primary EBV infection occurs at a very early age.
Biopsy specimens from nasopharyngeal carcinomas (NPC) or salivary-gland carcinomas (SGC) in Greenland Eskimoes were examined for the presence of Epstein-Barr virus (EBV) DNA and sera from the patients were tested for EBV-specific antibody titres. Six out of 7 NPCs and one from an undifferentiated SGG were positive for EBV DNA. The EBV-specific antibody spectra and titres of the patients with NPC or undifferentiated SGG conformed to the results of earlier studies in other high-incidence areas.
Salivary gland carcinoma (SGC) occurs at an increased frequency in the Eskimo population. In Greenland the incidence of SGC is 4.5-fold higher for men and 9-fold higher for women as compared with European incidence. The increased incidence is caused by low-differentiated carcinoma. Unusual familial clustering of SGC is reported among two families (five siblings). Peculiar aspects of racial and geographical distribution and possible role of genetic and environmental factors in the etiology of this relatively uncommon tumor are briefly discussed with special emphasis on the recently detected association between the Eskimos' SGC and the Epstein-Barr virus.
BACKGROUND. Nasopharyngeal carcinoma (NPC) and anaplastic salivary gland carcinoma (SGC), both associated with Epstein-Barr virus (EBV), are common among Inuit from Greenland, Canada, and Alaska. Because immigrant studies have shown that factors acting early in life are important for the development of NPC, the authors interviewed new patients in Greenland with either NPC or SGC about their lifestyles during childhood and additional cases in their families. METHODS. On admission, new patients from Greenland with either NPC or SGC were interviewed about childhood life-style, family size, and other cases of NPC or SGC within the family. Additional cases were confirmed by review of the medical records concerning these patients. RESULTS. During the 11 years from 1980 through 1990, 17 of 63 (27%) cases in Greenland were found in familial clusters among first-degree relatives. There were no differences in the life-styles of multiple-case families and single-case families. CONCLUSIONS. The high rate of familial clusters among natives of Greenland is of interest because EBV is believed to play a role in the origin of these two diseases similar to that of Marek disease in neurolymphomatosis of chickens. Therefore, the familial clustering of NPC and SGC may indicate that an enhanced oncogenic potential of an EBV strain may occur more frequently in Greenland than in other parts of the world.
The polymerase chain reaction was used to examine paraffin-embedded tissues of 37 nasopharyngeal carcinomas (NPC) for Epstein-Barr virus (EBV) genomic sequences. EBV DNA was found in 2/14 keratinising squamous cell (WHO 1) carcinomas and in all of 23 non-keratinising and undifferentiated (WHO 2 and 3) NPC. The study confirms the infrequent association of keratinising NPC and EBV, in contrast with the 100% association of the less differentiated NPCs and the virus. The results may indicate a different carcinogenesis for the WHO 1 NPC subtype.
Clinical data from 218 patients consecutively treated for nasopharyngeal carcinoma at the Finsen Institute in Copenhagen during the period 1965 through 1985 have been analyzed for factors of prognostic importance. Of the 218 patients, 47 were Greenland Inuit eskimos and 169 were white Danish. The 5-year crude survival for the entire group of patients was 30%. The two groups of patients differed with respect to the importance of different prognostic factors. Keratinizing tumors were only present in the Danish population. These patients had a highly significant worse outcome than the rest of the Danish (P less than 0.00001). Age, stage, and T classification were important prognostic factors in the Danish population, but not in the Inuit population.
Evidence of epidemicity of nasopharyngeal carcinoma (NPC) was sought in Greenland Inuits, who have a high incidence of this cancer, by examining the births of NPC cases for evidence of clustering in time and space. Births of cases were concentrated in autumn and winter. Fifty-four cases were analysed, and a two-fold excess of clustering within one year was observed, both within single districts and between adjacent districts. This excess was not significant at the 5% level; about 90 cases would have been required to confirm the observed effect at this level of significance. It is suggested that a search for space-time clustering of NPC cases in larger high-risk populations might prove more fruitful.