This is a two-part clinical trial. The first part will be a dose escalation phase involving preoperative radiation therapy to determine the maximum tolerated dose (MTD). The second part will be a dose expansion in which an additional 6 patients will be studied at the MTD for further experience with safety and efficacy. The dose escalation portion of the trial will have six cohorts or arms. Cohort 1 will receive the standard dose of 30 Gy in 5 fractions. Subsequent cohorts will have patients receiving 30 GY in 5 fractions to the planning target volume with dose-escalation of the gross tumor volume (GTV) to 35Gy, 40 Gy, 45 Gy and 50 Gy. An interim analysis will be performed after 40 Gy to assess toxicity.
The novel use of preoperative RT will have broad implications for breast cancer patients, most of whom present with early-stage disease. In the era of reduced chemotherapy delivery, preoperative RT will allow oncologists to assess radiologic and biologic tumor response and correlate it to outcomes. Underutilization of RT negatively affects mortality. This trial aims to further evaluate pre-operative radiation therapy in patients with early stage, biologically favorable breast cancer, with improved access to RT.