NGS-Based BRCA1, BRCA2, and PALB2 Mutation Testing in Iranian Population With Breast Cancer

Abstract

Background: Identification of individuals who have a pathogenic mutation in breast cancer susceptibility genes is an important step to take advantage of genetic counseling, screening, and potentially life-saving prevention strategies. Based on the National Comprehensive Cancer Network (NCCN) guideline, genetic testing is deemed suitable for breast cancer patients with young age at onset, positive family history of cancers, male breast cancer, or diagnosis with a multifocal or triple negative breast cancer. Aim: Since, it is not known what proportion of breast cancers in Iran is hereditary and related to mutations in BRCA1/2 and PALB2 genes, therefore, we screened these 3 genes in multiethnic Iranian population to determine the spectrum of the breast cancer susceptibility gene mutations and to further assess the predictive value of the hereditary breast cancer risk criteria for genetic testing. Methods: Next generation sequencing (NGS) was conducted on a population consisted of 299 and 125 breast cancer patients, with and without hereditary cancer risk criteria for genetic testing, respectively. Results: Pathogenic mutation rate was 10.36% in patients with hereditary criteria for breast cancer vs 1.6% in no criteria group ( P = 0.002). All the patients who only met the young age at onset (<40) criterion tested negative for a gene mutation. This is while patients who had only 1 hereditary criterion (OR: 5.48, 95% CI: 1.09, 52.90, P = 0.017) and patients with multiple hereditary criteria (OR: 22.5, 95% CI: 5.19, 201.31, P < 0.0001) had a significantly higher probability of finding a mutation compared with no risk-criteria group. Conclusion: The first application of NGS on Iranian breast cancer population added to the cumulative evidence that BRCA1/2 mutations are seen commonly among Iranian breast cancer patients especially those with hereditary breast cancer criteria and indicated that PALB2 should be concerned in hereditary breast cancer screening alongside BRCA1/2. Investigating the predictive potential of hereditary breast cancer risk criteria our results suggest that offering genetic testing to women with early age at onset of <40 with no other hereditary criteria, may not be cost effective and should be considered for optimization of genetic counseling and genetic testing of the Iranian population.