Safety of Omitting Radiotherapy After Lumpectomy in Early Breast Cancer — What the Randomized Evidence Says

Rodrigo Arrangoiz MS, MD, FACS, FSSO

Bottom line: In carefully selected patients (typically older, ER+/HER2–, node-negative, small tumors on endocrine therapy), skipping whole-breast radiotherapy (RT) raises local recurrence modestly but does not worsen overall survival in long-term randomized data. 

Key randomized signals (10-year):

• PRIME II (age ≥65, HR+, ≤3 cm, node-negative, endocrine therapy): local recurrence 9.5% without RT vs 0.9% with RT; no difference in distant recurrence or overall survival (~81% both arms). 

• CALGB 9343 (age ≥70, T1N0 ER+): local/regional control higher with RT (98% vs 90%) but no differences in time to mastectomy, distant metastasis, breast cancer-specific survival, or OS (67% vs 66%). 

Meta-analytic perspective: Syntheses focused on randomized trials consistently show RT substantially lowers local recurrence after breast-conserving surgery, with minimal or no OS impact in these low-risk cohorts—informing shared decisions when a patient prioritizes avoiding RT toxicity or logistics. 

Who may be appropriate to consider for omission?

• Age ≥65–70, ER+, HER2–, pT1, node-negative, clear margins, committed to endocrine therapy; ideally with a reassuring axillary assessment and low-risk biology. (Emerging prospective cohorts like LUMINA/IDEA support expanding biologic selection but are not RCTs.) 

Why this matters for patients:

• Fewer visits, less fatigue/dermatitis, and lower long-term toxicity burden—without sacrificing survival in the right subset. 

Practical takeaways for clinic:

Discuss omission for the classic low-risk profile above; quote absolute local-recurrence trade-offs (e.g., ~9–10% vs ~1% at 10 years in PRIME II).  If RT is preferred or biology is borderline, consider de-escalated RT (partial-breast or 5-fraction regimens) to cut burden while preserving control.  Use shared decision-making; align with patient goals, comorbidity, adherence to endocrine therapy, and imaging/pathology risk features. 

#BreastCancer #RadiationOncology #Deescalation #SharedDecisionMaking #Oncology

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Published by Rodrigo Arrangoiz MS, MD, FACS, FSSO

My name is Rodrigo Arrangoiz I am a breast surgeon/ thyroid surgeon / parathyroid surgeon / head and neck surgeon / surgical oncologist that works at Center for Advanced Surgical Oncology in Miami, Florida. I was trained as a surgeon at Michigan State University from (2005 to 2010) where I was a chief resident in 2010. My surgical oncology and head and neck training was performed at the Fox Chase Cancer Center in Philadelphia from 2010 to 2012. At the same time I underwent a masters in science (Clinical research for health professionals) at the University of Drexel. Through the International Federation of Head and Neck Societies / Memorial Sloan Kettering Cancer Center I performed a two year head and neck surgery and oncology / endocrine fellowship that ended in 2016. Mi nombre es Rodrigo Arrangoiz, soy cirujano oncólogo / cirujano de tumores de cabeza y cuello / cirujano endocrino que trabaja Center for Advanced Surgical Oncology en Miami, Florida. Fui entrenado como cirujano en Michigan State University (2005 a 2010 ) donde fui jefe de residentes en 2010. Mi formación en oncología quirúrgica y e n tumores de cabeza y cuello se realizó en el Fox Chase Cancer Center en Filadelfia de 2010 a 2012. Al mismo tiempo, me sometí a una maestría en ciencias (investigación clínica para profesionales de la salud) en la Universidad de Drexel. A través de la Federación Internacional de Sociedades de Cabeza y Cuello / Memorial Sloan Kettering Cancer Center realicé una sub especialidad en cirugía de cabeza y cuello / cirugia endocrina de dos años que terminó en 2016.

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