Cytogenetic differences between intestinal and diffuse types of human gastric carcinoma.

This study concerns the cytogenetics of 23 gastric carcinomas, classified histologically as intestinal or diffuse types. In carcinomas of the diffuse type, the only numerical changes observed were Y chromosome loss associated with X-chromosome disomy in four of seven male patients. 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 type tumors were exclusively aneuploid, with chromosome modes ranging from 48 to 84. The most consistent change was trisomy 20 in seven of 11 patients, each of which displayed a number of both single and clonal structural aberrations. Frequent structural changes were translocations involving chromosome 13 (including a putative isochromosome 13q in three of 11 patients), and alterations in chromosomes 1, 6 and 12. This study therefore suggests that diffuse and intestinal types of gastric carcinomas 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 aggressive tumors (intestinal type) show multiple changes, both numerical and structural, of which some are reminiscent of changes seen in tumors of the lower gastrointestinal tract. Cytogenetics may thus be a valuable adjunct in establishing the diagnosis, classification, and prognosis of gastric carcinomas.