Incidence of loss of heterozygosity at p53 and BRCA1 loci in serous surface carcinoma

Serous surface carcinoma (SSC) is a neoplasm histologically indistinguishab le from typical serous carcinomas that arise from the ovary bur has a disti nct clinical presentation. It is characterized by widespread peritoneal dis semination at presentation, but the ovaries are grossly normal in size and shape. If the carcinoma involves the ovaries microscopically, the tumor is confined to the surface or is minimally invasive, The recognition of this e ntity is important, because in some studies it appears to have a poorer pro gnosis than stage-matched serous cancers of the ovary. Loss of heterozygosi ty (LOH) of the p53 (17p) and BRCA1 (17q) tumor suppressor genes has been f requently identified in sporadic ovarian carcinomas. Although 17p LOH is co rrelated with common p53 gene mutations, inactivating mutations of the BRCA 1 gene are uncommon in sporadic ovarian cases. In contrast, germline BRCA1 mutations are responsible for some hereditary forms of ovarian cancer, wher e it has been suggested that germline BRCA1 mutations confer a more favorab le prognosis, In this study, 12 sporadic SSC were assessed for the presence of allelic deletions on the p53 and BRCA1 gene loci. DNA from both tumor a nd normal cells was obtained for LOH studies using tissue microdissection. Polymerase chain reaction (PCR) amplification was performed with the polymo rphic DNA markers TP53 (17p13.1/p53 gene) and D17S579 (17q/BRCA1 gene). LOH in the p53 and BRCA1 loci was detected in 62.5% and 66.6% of the cases, re spectively. In 50% of tumors informative for both markers, it is possible t hat an entire chromosome may be lost. In conclusion, we have shown that LOH of the p53 and BRCA1 loci is a frequent event in sporadic SSC, similar to what has been described in the usual form of serous ovarian carcinoma. Muta tional analysis will be necessary to determine the exact role of these gene s in this group of tumors. HUM PATHOL 30:203-207. This is a US government w ork. There are no restrictions on its use.