Multi-Gene Mutation Profiling by Targeted Next-Generation Sequencing in Premenopausal Breast Cancer

Breast cancer has distinct etiology, prognoses, and clinical outcomes at premenopausal ages. Determination of the frequency of germline and somatic mutations will refine our understanding of the genetic contribution to premenopausal breast cancer susceptibility. We applied a comprehensive next generation sequencing-based approach to analyze blood and/or tissue samples of 54 premenopausal breast cancer patients treated in our clinic. Genetic testing results were descriptively analyzed in correlation with clinicopathological data. In the present study, 42.5% of premenopausal breast cancer patients tested carried pathogenic mutations in cancer predisposition genes (<i>CHEK2</i>, <i>BRCA1</i>, <i>TP53</i>, and <i>MUTYH</i>). Germline variants of unknown/uncertain significance (VUSs) in eight different cancer susceptibility genes, namely <i>BRCA1</i>, <i>BRCA2</i>, <i>CHEK2</i>, <i>RAD51C</i>, <i>RAD51D</i>, <i>ATM</i>, <i>BRIP1</i>, and <i>PMS2</i>, were also identified in 14 premenopausal patients (35%). Of the breast tumors tested, 61.8% harbored pathogenic somatic variants in tumor suppressor genes (<i>TP53</i>, <i>NF1</i>, <i>RB</i>), genes involved in DNA repair (<i>BRCA1</i>, <i>BRCA2</i>, <i>ATM</i>, <i>RAD50</i>), cell proliferation (<i>PTEN</i>, <i>PIK3C FGFR3</i>, <i>AKT1</i>, <i>ROS1</i>, <i>ERBB2</i>, <i>NOTCH1</i>), and cell adhesion (<i>CTNNB1</i>). This descriptive study employs the powerful NGS technology to highlight the high frequency of premenopausal cases attributable to genetic predisposition. Mutation identification in a larger cohort may further ensure that these patients receive tailored treatment according to their menopausal status.