Postoperative Radiotherapy After Breast-Conserving Surgery for Early-Stage Breast Cancer: A Review.

IMPORTANCE: Radiotherapy (RT) after breast-conserving surgery for early-stage disease has become an integral part of breast cancer treatment. This article reviews the rationale and indications for adjuvant radiotherapy to the breast and regional lymph nodes. OBSERVATIONS: Randomized trials have demonstrated a significant benefit in tumor control in the treated breast following whole-breast RT that, in aggregate, has resulted in an overall survival advantage compared with breast-conserving surgery alone. Recent studies have further assessed the impact of regional nodal irradiation in women with either high-risk node-negative or node-positive disease and suggest a significant benefit in regional control and breast cancer recurrence, but not in overall survival. Toxic effects, including lymphedema, were increased in the cohorts receiving comprehensive nodal RT. The benefits from regional RT should be weighed against potential radiation-associated toxic effects. Randomized trials have also demonstrated equal efficacy and toxic effects between hypofractionated and conventionally fractionated RT in appropriately selected patients. In addition, current efforts incorporating clinical, pathologic, and molecular features are under way to identify patients for whom RT to the breast can be safely omitted. CONCLUSIONS AND RELEVANCE: Adjuvant RT in early-stage breast cancer significantly reduces in-breast tumor recurrence and improves overall survival. Although risk reductions observed in randomized trials have been relatively consistent across series, the absolute benefit of RT is not equal for all women. Efforts are under way to identify which patients benefit the most from local or locoregional RT vs those at very low risk for recurrence in whom RT can be omitted. For patients who will benefit from RT and are appropriate candidates, hypofractionated RT should be strongly considered.