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.