Clinical, Molecular and Geographical Features of Hereditary Breast/Ovarian Cancer in Latvia

Introduction. The aim of the study is to evaluate the incidence and phenotype-genotype characteristics of hereditary breast and ovarian cancer syndromes in Latvia in order to develop the basis of clinical management for patients and their relatives affected by this syndrome. Material and methods. In 2002-2004 in two Latvian oncology hospitals (Liepaja Oncology Hospital and Daugavpils Oncology Hospital) cancer family histories were collected from 287 consecutive patients with breast and ovarian cancer. In all cases, when it was possible to obtain the blood sample, DNA testing for founder mutations in the BRCA1 gene was performed. Results. Among 287 family cancer histories analysed in 8 (2.8%) cases criteria of hereditary breast cancer (HBC) were fulfilled and in 5 (1.7%) cases hereditary breast and ovarian cancer (HBOC) was diagnosed. In 50 (17.4%) cases we have suspicion of hereditary breast cancer (HBC susp.) and in 8 (2.8%) cases - suspicion of hereditary breast and ovarian cancer (HBOC susp.). We have one (0.3%) case with hereditary ovarian cancer (HOC). DNA testing of founder mutations in the BRCA1 gene (exon 20 (5382 insC) exon 5 (300T/G), exon 11, 17 (4153delA)) for 178/287 (62%) patients was performed. In 9/287 (4.9%) cases we found a mutation in the BRCA1 gene. 4 mutations were detected in exon 11, 17 (4153delA) and 4 mutations in exon 20 (5382 insC) and 1 in exon 5. Conclusions. Existing pedigree/clinical data suggest that in Latvia the clinical frequency of hereditary breast and ovarian cancer is around 5% of consecutive breast and ovarian cancer patients and suspicion of the syndrome is observed in another 20% of cases. Frequency of BRCA1 founder mutations is 5% of all consecutive breast and ovarian cancers. Considerable geographical differences in the clinical and molecular frequency of hereditary breast ovarian cancer have been observed in Latvia.