Ten percent of breast and ovarian cancer patients in Tyks expert responsibility area have pathogenic BRCA variant

Background The number of families counselled for breast and ovarian cancer in the expert responsibility area (erva) of Turku University Hospital (Tyks) has quadrupled during the past 10 years. In this study we investigated the number of BRCA families.

Methods The retrospective cohort study covers all families who have received counselling for breast or ovarian cancer by the Department of Clinical Genetics at Tyks since 1996. Altogether 904 gene analyses were done. Based on gene analyses or pedigree the number of high-risk families identified was 852. BRCA results of ovarian tumour samples (1/2017–6/2020) were analyzed.

Results The ratio of newly identified BRCA families to high-risk families was 9.6% (82/852). The number of family-specific mutations was 9 (24%) in the BRCA1 gene and 8 (18%) in the BRCA2 gene; other mutations are common in Finland. The ratio of BRCA2 gene VUS (variants of uncertain significance) to BRCA2 pathogenic variants was 30% (13/44). In addition, 144 ovarian tumour samples were analyzed, of which six were germinal (4.2%).

Conclusions The percentage of BRCA families amongst all high-risk families has decreased as test criteria have become less strict. The large number of BRCA2 VUS may reflect the large number of family-specific pathogenic variants in southwestern Finland. The number of germinal BRCA changes in ovarian cancer tumours is small. Knowledge on regional variant profiles will improve the analysis of gene results.

Terhi Pallonen, Pia Pohjola, Salla Lempiäinen, Titta Joutsiniemi, Minna Kankuri-Tammilehto

Minna Kankuri-Tammilehto

M.D., Ph.D., Specialist in Clinical Genetics

University of Turku and Turku University Hospital