Isochromosome 8q A Recurrent Change in Gastric Carcinoma Few reports have described the cytogenetic study of gastric cancer using banding methods [1-5]; most of them consist mainly [5] or exclusively [1, 2] of analyses of metastatic effusions from patients with adenocarcinoma of the stomach. These studies failed to show any recurrent structural abnormality, although some tumors gained chromosomes 3, 8, and 12 [6]. In the past 2 years, we studied 10 cytogenetically abnormal primary gastric adenoo carcinomas after short-term in vitro culture (manuscript in preparation). Nine of these tumors were in advanced stages (stages III-IV) and seven were of unclassified histologic type, according to the classification of Laur~n [7]. Most of the carcinomas (nine cases) showed massive genomic rearrangements, with frequent numerical abnormalities of chromosomes 3, 7, and 8. An i(8q) was detected in 100% of abnormal metaphases in three cases, all of the unclassified histologic type. A correlation of this histologic picture with the presence of the cytogenetic marker seems premature in view of the few cases studied and the limitations of the available histologic classifications of gastric cancer [8]. On the other hand, the cases with i(8q) presented at stages III (2 cases) and IV (1 case), all with lymphatic and vascular invasion. Because most tumors in our series were in advanced stages, it is difficult to relate the presence of the i(8q) to tumor progression, invasiveness, or both. An isochromosome 8q was previously described in one stage IV primary adenocarcinoma of the stomach [2] and in the ascitic and pleural effusions of a patient with advanced gastric cancer [4], however. Excess of (parts of) chromosome 8 [including i(8q)] has been described in a number of neoplasms, namely colorectal neoplasms [9, 10]. Moreover, trisomy 8 is a frequent secondary change in myeloid leukemias, independently conferring a relatively bad prognosis as compared with other cytogenetic abnormalities [6]. Thus, excess of 8q material (caused either by trisomy or by structural rearrangements, including isochromosome 8q) is a common event in advanced neoplasms, particularly gastric cancer. Although the oncogenetic relevance and prognostic implications of this change remain to be clarified in gastric cancer, it probably represents a secondary change, possibly related to (causing?) an aggressive biologic behavior of the tumor. This work was partially supported (I.N.I.C.).

by a

S~RGIO CASTEDO CECILIACORREIA LEONOR DAVID MANUEL SOBRINHO-SIMOES

grant from Instituto Nacional de Investigaq/~oCientifica Departments of Medical Genetics (S.C.) and Pathology (L.D., M.S.-S.) Medical Faculty of Porto, and the Department of Genetics (S.C., C.C.) Portuguese Institute for Oncology Porto, Portugal

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Cancer Genet Cytogenet 54:137-138 (1991) 0165-4608/91/$03.50

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