Hereditary breast-ovarian cancer syndrome in Russia.

Hereditary breast-ovarian cancer syndrome contributes to as much as 5-7% of breast cancer (BC) and 10-15% of ovarian cancer (OC) incidence. Mutations in the "canonical" genesBRCA1andBRCA2occur in 20-30% of affected pedigrees. In addition toBRCA1andBRCA2 mutations, germ-line lesions in theCHEK2,NBS1, andPALB2genes also contribute to familial BC clustering. The epidemiology of hereditary breast-ovarian cancer in Russia has some specific features. The impact of the "founder" effect is surprisingly remarkable: a single mutation,BRCA15382insC, accounts for the vast majority ofBRCA1defects across the country. In addition, there are two other recurrentBRCA1alleles:BRCA14153delA andBRCA1185delAG. BesidesBRCA1, in Russia breast cancer is often caused by germ-line alterations in theCHEK2andNBS1genes. In contrast toBRCA1andBRCA2, theCHEK2andNBS1heterozygosity does not significantly increase the OC risk. Several Russian breast cancer clinics recently started to investigate the efficacy of cisplatin in the therapy ofBRCA1-related cancers; initial results show a unique sensitivity ofBRCA1-associated tumours to this compound.

CHEK2 variants predispose to benign, borderline and low-grade invasive ovarian tumors.

OBJECTIVE: Three founder alleles of the CHEK2 gene have been associated with predisposition to a range of cancer types in Poland. Two founder alleles (1100delC and IVS2 + 1G >A) result in a truncated CHEK2 protein and the other is a missense substitution, leading to the replacement of a threonine with an isoleucine (I157T). METHODS: To establish if these variants play a role in the etiology of ovarian tumors, we genotyped 1108 Polish women with various types of ovarian tumors and 4000 controls for the three CHEK2 variants. We included 539 Polish women with benign ovarian cystadenomas, 122 women with borderline ovarian malignancies and 447 women with invasive ovarian cancer. RESULTS: Positive associations were seen with the CHEK2 I157T missense variant and ovarian cystadenomas (OR = 1.7; P = 0.005), with borderline ovarian cancers (OR = 2.6; P = 0.002) and with low-grade invasive cancers (OR = 2.1; P = 0.04). There was no association with ovarian cancer of high grade (OR = 1.0). The association between the I157T missense variant was then confirmed in a second sample of Russian patients with borderline ovarian cancers (OR = 2.7; P = 0.06). CONCLUSION: These data indicate that CHEK2 variants may predispose to a range of ovarian tumor types of low malignant potential, but not to aggressive cancers.