Genetic Considerations in the Locoregional Management of Breast Cancer: a Review of Current Evidence

Purpose of Review: Breast cancer is the most commonly diagnosed cancer and is the second leading cause of cancer death in women. Breast cancer screening has significantly improved detection of cancer and reduced mortality however, mortality has plateaued in recent years. As such, identifying ways to improve management decisions to further reduce mortality remains a high priority. Herein, we review the current evidence for locoregional management recommendations in patients with hereditary breast cancer mutations. Additionally, we discuss the potential utility of gene assays in locoregional management decision-making. Recent Findings: Gene assays are currently used to identify patients who would benefit from systemic adjuvant therapy, and their uptake has improved clinical outcomes. There is growing evidence supporting their utility in determining patients at a higher risk for locoregional recurrence. As such, gene assays may have a role in decision-making regarding the locoregional management of breast cancer, and specifically the use of adjuvant RT. Summary: Risk reduction is central to the management of patients with hereditary breast cancer mutations. In patients with BRCA1/2 mutations, risk-reducing mastectomy (RRM) ± adjuvant radiotherapy (RT) or breast conserving therapy (BCS) with adjuvant RT is often an appropriate treatment regimen. A similar treatment approach is likely appropriate in other high-penetrance mutations, although RT should be used cautiously in patients with TP53 mutations. In patients with low-moderate penetrance mutations, BCS with adjuvant RT or RRM in conjunction with patient preference is likely appropriate, although RT should be avoided in patients with ATM mutations.