Allelotype of papillary serous peritoneal carcinomas

Objective. Papillary serous peritoneal carcinoma (PSPC) is histologically i ndistinguishable from papillary serous ovarian carcinoma (PSOC) with a simi lar clinical presentation, yet may differ in its carcinogenesis. The purpos e of this study was to determine the incidence of allelic loss and the freq uency of p53 mutation by p53 overexpression in PSPC compared to PSOC. Methods. An allelotype analysis of 26 patients with PSPC was performed usin g 39 microsatellite markers from 25 chromosomal arms. Thirty-seven previous ly studied patients with PSOC served as the comparison. P53 mutations were detected by immunohistochemical protein overexpression. Results. There was significantly less LOH in PSPC than PSOC. Both the numbe r of chromosomes with LOH and the proportion of tumors with allelic loss we re less frequent. Significant LOH, defined as greater than or equal to 30% of informative tumors having loss at a chromosome locus, was seen on 4 chro mosome arms in PSPC: 12p, 17p, 17q, and 18q, compared to 18 arms in PSOC: 4 q, 5q, 6p, 6q, 9p, 90, 12p, 12q, 13q, 15q, 16q, 17p, 17q, 18q, 19p, 190, 22 q, and Xq (P < 0.001). The median LOH frequency was higher in PSOC than PSP C, 43% versus 33%, respectively (P = 0.013), and more PSOC tumors had LOH t han PSPC tumors, 91% versus 65% (P = 0.042). P53 overexpression was detecte d in 80% of PSPC tumors. Conclusions. LOH occurs less frequently in PSPC compared to PSOC. Chromosom al regions with high frequencies of LOH common to PSPC and PSOC, such as 12 p, 17p, 17q, and 18q, may harbor tumor suppressor genes important in the ca rcinogenesis of both malignancies and likely include p53. (C) 2001 Academic Press.