Postmastectomy radiation after the 2025 guideline: what it recommends and what the ten-year trial found

Postmastectomy radiation therapy (PMRT) is treatment of the chest wall or reconstructed breast and the ipsilateral regional nodes after mastectomy ^[1]. On 16 September 2025, the American Society for Radiation Oncology, the American Society of Clinical Oncology and the Society of Surgical Oncology published a joint PMRT guideline ^[2][1]. The guideline rests on a systematic review ^[2]. On 6 November 2025, a randomized trial of 1,607 patients with intermediate-risk disease found no difference in ten-year overall survival with chest-wall irradiation ^[3].

What does the 2025 joint guideline say?

The joint guideline's recommendations cover indications, technique and bolus ^[2][1]:

• Upfront mastectomy: the guideline states that PMRT is indicated for most patients with node-positive disease and for select patients with node-negative disease ^[2].
• After neoadjuvant therapy: the guideline recommends PMRT for locally advanced presentations and for residual nodal disease at surgery ^[2].
• Nodal conversion: the guideline gives only a conditional recommendation for cT1-3N1 or cT3N0 disease that becomes pathologically node negative (ypN0) ^[2].
• Technique: the guideline favors moderate hypofractionation, with conventional fractionation acceptable in rare cases ^[1].
• Bolus: the guideline supports a bolus for skin involvement, positive superficial margins or lymphovascular invasion, but not routine use of tissue-equivalent bolus ^[1].

What did the ten-year randomized trial measure?

In the trial, intermediate risk meant pT1-2N1, pT3N0, or pT2N0 with grade 3 histology or lymphovascular invasion, after mastectomy, axillary surgery and systemic therapy ^[3]. At a median follow-up of 9.6 years, ten-year overall survival was 81.4% with chest-wall irradiation and 81.9% without (hazard ratio 1.04, 95% CI 0.82 to 1.30) ^[3]. In the trial, chest-wall recurrence occurred in 1.1% of irradiated and 2.5% of unirradiated patients (difference under 2 percentage points; hazard ratio 0.45, 95% CI 0.20 to 0.99) ^[3]. The trial found disease-free survival of 76.2% with and 75.5% without irradiation (hazard ratio 0.97, 95% CI 0.79 to 1.18), and distant metastasis-free survival of 78.2% and 79.2% (hazard ratio 1.06, 95% CI 0.86 to 1.31) ^[3]. The trial's definition includes pT1-2N1 disease, which falls under the guideline's node-positive indication ^[2][3]. The trial reported its ten-year result after the guideline was published ^[2][3].

In the 2026 Lancet Oncology five-year quality-of-life substudy of that trial (989 UK participants), chest-wall symptoms were worse with radiotherapy (effect estimate 1.99, 95% CI 0.36 to 3.62) ^[4]. The substudy found no significant differences in arm symptoms, body image, fatigue, pain, overall quality of life, physical functioning, or anxiety and depression ^[4].

What did the older meta-analysis find?

The 2014 meta-analysis by the Early Breast Cancer Trialists' Collaborative Group of 22 trials (8,135 women, randomized 1964 to 1986) found lower breast cancer mortality with radiotherapy for 1,314 women with one to three positive nodes (rate ratio 0.80, 95% CI 0.67 to 0.95) ^[5]. For 700 node-negative women in the 2014 meta-analysis, radiotherapy had no significant effect on recurrence or breast cancer mortality ^[5]. The authors noted that for today's women, who in many countries are at lower risk of recurrence, absolute gains might be smaller but proportional gains might be larger ^[5].

Where is the evidence uncertain?

A 2025 meta-analysis of 16 studies in ypN0 disease after neoadjuvant chemotherapy associated PMRT with lower locoregional recurrence across ten studies (risk ratio 0.52, 95% CI 0.41 to 0.67) ^[6]. The same ypN0 meta-analysis reported a marginal overall survival increase across nine studies (risk ratio 1.01, 95% CI 1.00 to 1.02) and no significant disease-free survival effect across six (risk ratio 1.01, 95% CI 0.95 to 1.08) ^[6]. After immediate reconstruction, a 2025 meta-analysis of 11 studies (3,611 patients) compared moderate hypofractionation with conventional fractionation ^[7]. The reconstruction meta-analysis found similar major complication risks (odds ratio 0.83, 95% CI 0.51 to 1.35, a wide interval) ^[7]. That meta-analysis also reported lower capsular contracture with hypofractionation (odds ratio 0.38, 95% CI 0.15 to 0.99, an upper limit just below 1), and only one study assessed quality of life ^[7].

At the point of care: what to check

• Nodal status before and after neoadjuvant therapy, and cT category: the guideline's indications turn on these ^[2].
• Whether the patient meets the trial's intermediate-risk definition (pT1-2N1, pT3N0, or pT2N0 with grade 3 histology or lymphovascular invasion) and received systemic therapy ^[3].
• Pathologic nodal response in cT1-3N1 or cT3N0 disease after neoadjuvant therapy: ypN0 carries only a conditional recommendation ^[2].
• Immediate reconstruction and the fractionation used, the setting of the complication data comparing moderate hypofractionation with conventional fractionation ^[7].
• Chest-wall symptoms, the quality-of-life domain that was worse with radiotherapy in the substudy ^[4].