CYTOGENETIC DIFFERENCES BETWEEN INTESTINAL AND DIFFUSE TYPES OF HUMANGASTRIC-CARCINOMA

This study concerns the cytogenetics of 23 gastric carcinomas, classif ied histologically as intestinal or diffuse types. In carcinomas of th e diffuse type, the only numerical changes observed were Y chromosome loss associated with X-chromosome disomy in four of seven male patient s. A 46, XX karyotype without recognizable alterations was observed in three of five female patients, and rare structural changes in diffuse carcinomas involved chromosomes 1 and 18. In contrast, intestinal typ e tumors were exclusively aneuploid, with chromosome modes ranging fro m 48 to 84. The most consistent change was trisomy 20 in seven of 11 p atients, each of which displayed a number of both single and clonal st ructural aberrations. Frequent structural changes were translocations involving chromosome 13 (including a putative isochromosome 13q in thr ee of 11 patients), and alterations in chromosomes 1, 6 and 12. This s tudy therefore suggests that diffuse and intestinal types of gastric c arcinomas do not share a common sequence of genetic changes. The tumor with the worse prognosis (diffuse type) is surprisingly diploid, with uniform X-disomy in both males and females. The clinically less aggre ssive tumors (intestinal type) show multiple changes, both numerical a nd structural, of which some are reminiscent of changes seen in tumors of the lower gastrointestinal tract. Cytogenetics may thus be a valua ble adjunct in establishing the diagnosis, classification, and prognos is of gastric carcinomas.