P-RAD(+)TN - DCT

You are being asked to take part in this study because you have triple negative (TN) breast cancer that has spread to your lymph nodes. You are also planning to get chemo-immunotherapy treatment before surgery. Radiation therapy (RT) has been shown to improve the body's immune response against tumors when it is given with a drug called pembrolizumab. The purpose of this study is to find the best and safest dose of radiation (low or high) when given with pembrolizumab. Radiation is measured in Gy (pronounced "gray"). You will be randomly assigned (like flipping a coin) to receive either a low dose RT boost (9 Gy) or a high dose RT boost (24 Gy). The RT will be given with one dose of pembrolizumab. This is a hybrid decentralized study where some if not all assessments may be performed close to your home.