Prevalence of deleterious mutations among patients with breast cancer referred for multigene panel testing in a Romanian population.

Aim: Multigene panel testing for Hereditary Breast and Ovarian Cancer (HBOC) using next generation sequencing is becoming more common in medical care.We report our experience regarding deleterious mutations of high and moderate-risk breast cancer genes (BRCA1/2, TP53, STK11, CDH1, PTEN, PALB2, CHEK2, ATM), as well as more recently identified cancer genes, many of which have increased risk but less well-defined penetrance.

Methods: Genetic testing was performed in 130 consecutive cases with breast cancer referred to our clinic for surgical evaluation and who met the 2016 National Comprehensive Cancer Network (NCCN) criteria for genetic testing.

Results: 82 patients had pathogenic/likely pathogenic mutations and VUS mutations, and 48 were negative; 36 of the pathogenic mutations were in the high-risk genes and 16 were in the moderate risk genes and only 5 cases in the intermediary risk group.From the VUS mutation group 21 cases were in the intermediary risk group, 9 cases were in the moderate risk group and only 7 cases in high risk group.The most frequent BRCA1 variant was c.3607C>T (7 cases) followed by c.5266dupC and c.4035delA (each in 4 cases). Regarding BRCA-2 mutations we identified c.9371A>T and c.8755-1G>A in 6 cases and we diagnosed VUS mutations in 3 cases.

Conclusion: Our study identified 2 mutations in the BRCA1 gene that are less common in the Romanian population, c.3607C>T and c.4035delA. Both variants had particular molecular phenotypes, c.3607C>T variant respecting the triple negative pattern of BRCA1 breast cancer while c.4035delA were Luminal B HER positive.