Genomics and PBI: Tumor-Derived Target Amplification in Luminal B Patients and Implications for Therapy

Abstract

Breast conserving surgery followed by postoperative breast irradiation is the treatment of choice for early stage breast cancers. Four phase III trials have demonstrated equal survival and non-inferior local tumor control with partial breast irradiation (PBI) in comparison to standard 5-6 week whole breast irradiation (WBI) in appropriately selected patients. Less favorable tumor biology is associated with higher local and systemic failures with all local therapy options. Current Next Generation Sequencing assays have empowered in-depth signatures of these cancers, providing hope for further customization of care. These new tests have potential to influence treatment decisions, such as WBI vs. PBI and the sequencing of that treatment. Oncotype and Mammoprint predict prognosis and chemotherapy benefit, and could impact local therapy choices. Tumor cell genetic sequencing could be the future to determine what therapies are best for each tumor, or more importantly which tumor biologies are resistant to certain therapies. As a step in this direction, we examined genomics for Luminal B breast cancers treated by PBI.