EPSTEIN-BARR VIRUS IN GASTRIC CARCINOMA IS ASSOCIATED WITH LOCATION IN THE CARDIA AND WITH A DIFFUSE HISTOLOGY: A STUDY IN ONE AREA OF CHILE Alejandro CORVALAN 1 * , Chihaya KORIYAMA 2 , Suminori AKIBA 2 , Yoshito EIZURU 3 , Claudia BACKHOUSE 1 , Mariana PALMA 1 , Jorge ARGANDO ˜ NA 1 and Masayoshi TOKUNAGA 4 1 Instituto Chileno Japones de Enfermedades Digestivas, Hospital Clinico San Borja Arriaran, Santiago, Chile 2 Department of Public Health, Faculty of Medicine, Kagoshima University, Kagoshima, Japan 3 Division of Oncogenic and Persistent Viruses, Center for Chronic Viral Diseases, Faculty of Medicine, Kagoshima University, Kagoshima, Japan 4 Kodama Hospital, Kagoshima, Japan Epstein-Barr virus (EBV) has been associated with the most common form of stomach neoplasms, the gastric car- cinoma (GC). The presence of EBV-encoded small RNA- type-1 (EBER-1), a marker for EBV infection was analyzed by in situ hybridization (ISH) in 185 formalin-fixed and paraffin- embedded cases of GC from a high risk region. We found 31 (16.8%) EBV-positive cases with no relationship to age. Al- though male predominance (19% in males and 12.5% in fe- males) was observed, the gender difference did not achieve statistical significance. Odds ratio (OR) for cardia location was 5.4 (95% CI 1.7–17.3) when antrum was used as referent category and the effects of gender and age were taken into account. The proportion of EBV-positive cases in diffuse his- tology was higher than intestinal type (OR  4.8, 95% CI  2.0 –11.1). Our findings are contrary to a previously accepted hypothesis, that high-risk countries for GC have low rates of EBV-associated GC. In addition, our findings regarding loca- tion, histology and weak male predominance are different from what has been described in Asian and European coun- tries, but similar to those described in Mexico and Mexican descendants living in the U.S. suggesting unique characteris- tics of EBV-associated GC in Latin-America. © 2001 Wiley-Liss, Inc. Key words: Epstein-Barr virus; gastric cancer; neoplasms Epstein-Barr Virus (EBV) has been associated with lymphoid malignancies including Burkitt lymphoma, B-cell lymphoma from immunosuppressed patients and Hodgkin disease 1 as well as epi- thelial malignancies like nasopharyngeal carcinoma (NPC). 2,3 In addition to NPC, EBV has been implicated in the pathogenesis of lymphoepithelioma (LE), an undifferentiated carcinoma with prominent lymphoid stroma from several organs including salivary glands, parotid 4,5 and stomach. 6–8 Nevertheless, in the stomach, LE is a rare neoplasm representing only 4% of stomach neo- plasms. 9 Recently, direct evidence of EBV involvement in gastric carci- noma (GC), the most common form of stomach neoplasms, has been provided by the uniform presence of EBV in all tumor cells by EBV-encoded small RNA type-1 (EBER-1) in situ hybridiza- tion. 10,11 Also the detection of monoclonal EBV episomes by Southern blot 12 and the presence of elevated IgG and IgA anti- bodies against viral capsid antigen 12–14 are further evidence to support the association between EBV and GC. The prevalence of EBV-associated GC ranges from 6.9 – 18%. 11,15–19 Clinicopathologic features of EBV-associated GC demonstrate a male predominance, preferential location in the cardia and middle part of the stomach and equal distribution between intestinal and diffuse histological type. 11,16 In early cases of EBV-associated GC, a unique morphological pattern, denominated “lace pattern,” has been described. 20 This pattern consists of tumor cells forming small glands with back to back branching structures and lymphocytic infiltration in and around the carcinoma nest in the mucosa, and has been considered a biomarker of EBV involvement in early GC. 20 Even though the incidence of GC has decreased markedly during the past 50 years, 21 Chile remains a high-risk country for GC with age-adjusted mortality of 45/100,000 habitants for males and 25/100,000 for females in 1984. 22 Simultaneously, several authors have reported an increasing incidence of GC at cardia. 23,24 In this country, Csendes et al. 25 also reported an increase in the proportional frequency of cardia lesions over a 30-year period (26.8% in 1958 to 42.3% in 1990), in parallel with a decreased frequency of antrum lesions. In addition, they found an increased frequency of diffuse histological type lesions in the same series. 25 Because it has been reported that EBV-associated GC is pre- dominately located in the upper part of the stomach, and given the increased frequency of GC at the cardia, we were interested in analyzing the characteristics of EBV-associated GC in a high-risk region. MATERIAL AND METHODS Patients and samples Two hundred and four consecutive surgically resected GC cases were analyzed in our study. Cases were obtained from the archives of the Instituto Chileno, Japones de Enfermedades Digestivas, Hospital Clinico San Borja Arriaran, Santiago, Chile between 1993–97. From each case, formalin-fixed and paraffin-embedded blocks together with demographic and clinico-pathological data retrieved from medical records were analyzed. Nineteen cases were excluded because they had no information on ethnicity (8 cases), the final diagnosis was other than GC (8 cases) or there were no surgical specimens available (3 cases). Thus, a total of 185 GC cases were used in the present analysis. Based on family names, 183 cases were of Caucasian origin, 2 were Amerindian and none of them were Japanese migrant cases. Selected paraffin blocks including tumor and non-tumor tissue were stained by hematoxylin-and-eosin (H&E) for histological classification and by in situ hybridization (ISH) to detect the presence of EBV. Pathological data Site of tumor was classified according to the predominant loca- tion of the lesion as cardia (all gastric mucosa within 5 cm of the Grant sponsor: Ministry of Education, Science, Sports and Culture, Japan; Grant numbers: 12218231, 09042007. *Correspondence to: Instituto Chileno Japones de Enfermedades Diges- tivas, Hospital Clinico San Borja Arriaran, Av. Santa Rosa 1234 Santiago 10, Chile. Fax: +56-2-5555074. E-mail: acorvalan@mi-mail.cl Received 28 July 2000; Revised 21 November 2000, 5 February, 29 May 2001; Accepted 11 June 2001 Int. J. Cancer: 94, 527–530 (2001) © 2001 Wiley-Liss, Inc. Publication of the International Union Against Cancer