Assessing the Need for Adjusted Organ-at-Risk Planning Goals for Patients Undergoing Adjuvant Radiation Therapy for Locally Advanced Breast Cancer with Proton Radiation

PurposeLocally advanced breast cancer requires surgical management via lumpectomy or mastectomy with without systemic therapy followed by chest wall (CW) and comprehensive nodal irradiation (CNI). Radiation (RT) dose constraints for the heart ipsilateral lung have been developed based on photon RT. Proton (PBT) can deliver significantly lower doses of RT to these organs-at-risk (OARs) may warrant adjustments OAR planning goals.Methods MaterialsThe plans consecutive patients undergoing adjuvant CW-CNI PBT within a single center were reviewed. A inital treatment volume, comprised CW/intact + CNI (CTV_init) structure, including CW but excluding any boost was analyzed. Frequency distributions generated received heart, lungs, esophagus validated dosimetric parameters. then stratified laterality compared using Kruskal-Wallis H test. The 75th, 85th, 95th percentiles each parameter calculated, overall laterality. 75th percentile (Q3), used as suggested primary goal, secondary goal.ResultsOne hundred seventy-two Forty-nine right-sided, 107 left-sided, 16 bilateral. Q3 mean V25 1.5 Gy 1.7%, respectively. differed Pulmonary values similar current recommendations. For all lateralites, median volume receiving 70% prescription ≤1 cm3.ConclusionsWe present first study providing complete dose-volume histograms data pencil-beam scanning-PBT locally cancer, detailed information central tendencies, ranges data. We provided goals metrics esophagus; latter 2 differing from Quantitative Analysis Normal Tissue Effects in Clinic (QUANTEC) classical goals.