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Ovarian cancer is the fifth most common malignancy among North American women and the fourth leading cause of cancer death. Approximately 5 to 13% of all ovarian cancer cases are caused by the inheritance of cancer predisposing genes with an autosomal pattern of transmission.1 Hereditary ovarian carcinoma has been described in association with mutations in four genes, BRCA1 , BRCA2 , MLH1 , and MSH2 , although usually ovarian carcinoma (OC) does not occur in a site specific fashion, but is associated with breast cancer ( BRCA1 and BRCA2 ) or colorectal and endometrial cancer ( MLH1 and MSH2 ). The large majority of hereditary OC is attributable to mutations in BRCA1. While mutations in BRCA1 have been seen in large pedigrees with apparently site specific OC predisposition,2 mutations in BRCA2 that have been associated with site specific OC are rare, and have often been missense mutations.3,4 The biological significance of such mutations can be uncertain. Gayther et al 5 reported that mutations in a 3.3 kb segment of exon 11 of BRCA2 were associated with a higher risk of OC relative to breast cancer than were mutations outside this region (p = 0.0004). They called this region of BRCA2 the ovarian cancer cluster region (OCCR). In an expanded study from the same group, Thompson et al 6 estimated that mutations in the ovarian cancer cluster region (OCCR) of BRCA2 are associated with an OC risk to the age of 70 of 19.5% (95% confidence interval (CI) 11.6 to 31.7), whereas the equivalent risk associated with mutations outside this region has been estimated at 10.9% (95% CI 5.5 to 20.9). Despite the concluding comments of the authors, urging a cautious interpretation of their data, if these estimates were to be used to counsel women who carry BRCA2 mutations, those who …