The study population of the companion study will consist of newly enrolled RadComp trial participants. Patients on this ancillary will be consented prior to RadComp randomization to decrease the bias secondary to RT type and enhance internal validity. The study will define the early changes in biomarkers, imaging measures, and RT dose volume metrics and long-term (5-10 year) CV clinical outcomes using the RadComp parent study's infrastructure for clinical data collection and long-term follow-up. Blood samples, echocardiograms, and questionnaires are obtained at baseline (between end of chemotherapy and start of RT), immediately after the end of RT, and at 6 months and 12 months after the end of RT. An additional blood sample will be collected at 4 weeks after the start of RT. Clinical, demographic, and patient reported outcomes data are collected as part of the RadComp parent study. In addition to data collected by RadComp, we will collect a limited set of clinical data and two additional quality of life instruments for the companion study.
