Molecular similarities between primary peritoneal and primary ovarian carcinomas.

The objective of this paper was to characterize expression patterns of biologic markers to distinguish papillary serous peritoneal carcinoma (PPC) from papillary serous ovarian carcinoma (POC). Immunohistochemical analysis of HER-2/neu, p53, bcl-2, and nm23-H1 expression was performed on archival paraffin-embedded tissues. Antigen expression was compared at ovarian and extra-ovarian sites. Thirty-two PPC cases were compared to 18 POC cases. Mean age, stage, grade, and survival outcome were comparable between the two groups. Antigen expression patterns were not significantly different between PPC and POC for the four markers studied. In all cases, nm23-H1 was expressed. Conversely, bcl-2 was expressed at only a single tissue site in three of 32 (9.4%) PPC cases and in one of 18 (5.6%) POC cases. Eleven of 32 (34.4%) PPC cases overexpressed HER-2/neu, vs. four of 18 (22.2%) POC cases. P53 staining results were positive in 23 of 32 (71.9%) PPC and 13 of 18 (72.2%) POC cases. Intrapatient antigen expression was identical at primary and metastatic tumor sites in 50% of the POC and 48.4% of the PPC cases. We conclude that PPC and POC have a comparable immunohistochemical phenotype for these four molecular markers, which is reflected by their similar clinical courses.