Brca1 gene mutations in women with papillary serous carcinoma of the peritoneum

Objective: To compare BRCA1 mutations in papillary serous carcinoma of the peritoneum and papillary serous ovarian carcinoma. Methods: Germline DNA from 17 consecutive patients with peritoneal carcinoma was screened for mutations in the BRCA1 gene using single-strand conformation polymorphism analysis. Shifted DNA bands were sequenced. Patients with germline BRCA1 mutations were screened for allelic loss in tumor DNA at the BRCA1 locus. Results: Two of the 17 patients (11%, 95% confidence interval 0.07, 0.37) exhibited the 185 delAG germline BRCA1 mutation described in the Ashkenazi Jewish population. The family history of one patient was notable for a mother and five aunts with breast or ovarian cancer. The other patient had a personal history of breast cancer. Both patients exhibited allelic loss of the normal BRCA1 allele in their tumor. A third patient was found to have a previously undescribed exon 11 single base pair substitution at nucleotide 1239 (CAG to CAC) resulting in a missense mutation (Gln to His). The patient had no family or personal history of breast or ovarian cancer, and her tumor did not exhibit loss of heterozygosity. Conclusion: Germline BRCA1 mutations occur in papillary serous carcinoma of the peritoneum with a frequency comparable to the BRCA1 mutation rate in ovarian cancer. Although the penetrance is unknown, peritoneal carcinoma should be considered a malignancy expressed in the familial breast ovarian cancer syndrome.