Ultra-hypofractionated Whole Breast Irradiation With Lumpectomy Cavity Boost for the Treatment of Stage I-III Breast Cancer

PRIMARY OBJECTIVE: I. To evaluate the impact of UF-WBI + CB as assessed by patient-reported Global Cosmesis Score (GCS) at 1 year. SECONDARY OBJECTIVES: I. To characterize the patient-reported cosmetic appearance of the breast over time, as assessed by GCS. II. To determine short- and long-term physician-reported cosmetic appearance of the breast, as assessed by GCS. III. To evaluate the acute and late patient-reported radiation-associated toxicities. IV. To evaluate the acute and late physician-reported radiation-associated toxicities. V. To estimate: Va. 5-year in-breast recurrence; Vb. 5-year distant recurrence; Vc. 5-year disease-free survival (DFS); Vd. 5-year overall survival (OS). EXPLORATORY OBJECTIVES: I. To evaluate patient-reported quality-of-life (QoL). II. To evaluate volumetric and dosimetric factors associated with acceptable breast cosmesis. III. To evaluate volumetric and dosimetric factors associated with acute and late radiation-associated toxicities. OUTLINE: Patients undergo UF-WBI with CB once daily (QD) on consecutive business days for up to 5 fractions in the absence of disease progression or unacceptable toxicity. Additionally, patients undergo cone-beam computed tomography (CBCT) prior to each radiation treatment. After completion of study treatment, patients are followed up at 1 month, 6 months, then annually for up to 5 years.