Deng Hong (1940- ) is a native of Wuzhou, Guangxi. He is vice president, associate chief physician of Research Institute of Prevention and Cure of Tumor. Before 1978, he had been engaged in clinical ophthalmological and otolaryngological work. Since 1979, he has been specially engaged in prevention and cure of nasopharynx cancer of high incidence fields. His major achievement included: he launched general serological survey to a number of 330,000 people on their IgA/VCA antibodies to EB virus, which lasted 2 years. The result of survey proved that detection on IgA/VCA antibodies to EB virus can greatly improve the diagnosis ratio of early nasopharynx cancer and that EB virus plays a vital role in development of nasopharynx cancer; He also launched Level-II prevention to nasopharynx cancer in Wuzhou, Guangxi, which made 5-year survival rate of nasopharynx cancer patient in Wuzhou increased from 25% of that 10 years ago to 54.62%, reaching to the standard formulated by Ministry of Health on prevention and cure of tumor in Year 2000 Development Outline 10 years beforehand. He had also written or co-written about 50 theses which were published on foreign and domestic publications. His research achievement won Science and Technology Progress Award, awarded by Ministry of Health and State Science and Technology Commission.

EARLY DIAGNOSIS, PROSPECTIVE AND ETIOLOGICAL STUDIES ON NASOPHARYNAGEAL CARCINOMA

Zeng Yi, Wang Peizhong and Deng Hong

(Institute of Virology, Chinese Academy of Prevention Medicine Guangxi Autonomous Regional Hospital Wuzhou Cancer Institute)

Abstract

Nasopharyngeal carcinoma (NPC) is common in southern China. The purpose of our studies was to establish simple and sensitive techniques for early diagnosis of NPC and to clarify the role of Epstein-Barr (EB) virus, environmental factors and genetic factors in the development of NPC.

EB Virus and NPC

Early diagnosis and prospective studies are given below. Serological mass surveys of NPC were carried out in NPC high risk areas (Cangwu County and Wuzhou City) by immunoenzymatic test, and IgA/VCA antibody positive persons were followed up yearly for 10 years. The early detection rate increased from 18.6% to 81% in Cangwu County and from 32% to 92% in Wuzhou City. In the course of following-up IgA positive asymptomatic individuals, IgA/VCA antibodies could be detected 12 years before NPC onset. The IgA antibody titers were also followed up, 40.7%and 7.3% of IgA antibody positive persons had antibody titer stable and increasing, respectively. It is interested that most of NPC were detected from the group with increasing or stable IgA antibody titer. The titer of IgA antibody to VCA and EA is proportional to the detection rate of NPC. These data indicate that the detection of IgA antibodies to EB virus VCA and EA is very useful for early diagnosis of NPC. Beside IgA/VCA and IgA/EA antibodies, IgA/MA, IgA/EBNA-1and IgG/Z antibodies are also specific and valuable for NPC diagnosis.

EB Virus Inducers and Tumor Promoters

Ether extracts from 1693 plants ,including Chinese medicinal herbs ,were studies for EB virus inducer activity and more than fifty were found to have inducing activity. Many plants such as Aleurites fordii, Wikstroemia indica, Sapium sebiferum and Euphorbia antiquorum grow in high risk areas for NPC. EB virus inducers were found in the soil and they were also found in vegetables growing in such soil in southern China. Extracts from plants and herbs containing EB virus inducers can enhance lymphocyte transformation by EB virus in vitro as well as tumor growth by the Rous sarcoma virus, rabbit papillomavirus, DMBA, methylcholanthrene and dinitrosopiperazine (DNP).

The salted fish from southern China and harisa and qaddid from Tunisia contain EB virus inducers. These preserved foods are very frequently consumed in high risk areas for NPC. Mutagens were also detected in the same food extracts, this being the first time that EB virus inducers and mutagens were found to be present in the same foods. Our data demonstrate that EB virus inducers can enhance lymphocyte transformation by the virus as well as promote the development of NPC in rats by DNP.

The genetic basis for NPC

Linkage studies were started in an attempt to demonstrate the existence of a disease susceptibility gene closely linked to HLA locus A and B but distinct from them which would confer a high relative risk for this disease. A total of 29 sibships with more than one case of NPC were studied. This study has provided clear evidence for the existence of NPC disease susceptibility gene, tightly linked to the HLA region.

In conclusion, the etiological factors for the development of NPC are complicated, the EB virus plays an important role in the development of NPC, but it is not the unique factor, the genetic factor and the environmental factors are also involved in the development of NPC.