“When Less is More”: Paradigm Shifts in Radiation Treatment for Early-Stage Breast Cancer

Opinion Statement Recent advancements in the treatment of early-stage breast cancer have significantly shifted the radiotherapy landscape. Traditionally, the standard of care included lumpectomy followed by endocrine therapy and 3–5 weeks of adjuvant radiation targeting the entire unilateral breast. This review summaries modern trials, emphasizing data reported since 2019 that have changed radiation treatment paradigms. Ultra-hypofractionated treatment regimens have enabled radiation oncologists to deliver the total radiation dose in as few as 5 treatments over 1 week for select patients. Partial breast irradiation, treating only the breast tissue nearest to the lumpectomy cavity, has also emerged as an effective and well-tolerated treatment. Furthermore, a growing body of evidence supports the safety of omitting radiation completely for certain older adults with low-risk disease. Ongoing research in areas such as precision cancer care, treatment de-escalation, and toxicity prevention and management reflects a broader shift toward shared decision-making in medicine and individually tailored treatment paradigms. As research progresses, treatment options will continue to evolve. Advances in radiation oncology will give the oncology team a growing array of tools to custom treatment plans to individual patient risks and toxicity concerns. Knowledge of radiation advances should be used to facilitate shared decisions with patients about the balance of treatment efficacy, toxicity, and quality of life, with the ultimate goal of promoting high-quality, personalized, and patient-centered cancer care.