Summary Background If treatment of the axilla is indicated in patients with breast cancer who have a positive sentinel node, axillary lymph node dissection is the present standard. Although axillary lymph node dissection provides excellent regional control, it is associated with harmful side-effects. We aimed to assess whether axillary radiotherapy provides comparable regional control with fewer side-effects. Methods Patients with T1–2 primary breast cancer and no palpable lymphadenopathy were enrolled in the randomised, multicentre, open-label, phase 3 non-inferiority EORTC 10981-22023 AMAROS trial. Patients were randomly assigned (1:1) by a computer-generated allocation schedule to receive either axillary lymph node dissection or axillary radiotherapy in case of a positive sentinel node, stratified by institution. The primary endpoint was non-inferiority of 5-year axillary recurrence, considered to be not more than 4% for the axillary radiotherapy group compared with an expected 2% in the axillary lymph node dissection group. Analyses were by intention to treat and per protocol. The AMAROS trial is registered with ClinicalTrials.gov, number NCT00014612. Findings Between Feb 19, 2001, and April 29, 2010, 4823 patients were enrolled at 34 centres from nine European countries, of whom 4806 were eligible for randomisation. 2402 patients were randomly assigned to receive axillary lymph node dissection and 2404 to receive axillary radiotherapy. Of the 1425 patients with a positive sentinel node, 744 had been randomly assigned to axillary lymph node dissection and 681 to axillary radiotherapy; these patients constituted the intention-to-treat population. Median follow-up was 6·1 years (IQR 4·1–8·0) for the patients with positive sentinel lymph nodes. In the axillary lymph node dissection group, 220 (33%) of 672 patients who underwent axillary lymph node dissection had additional positive nodes. Axillary recurrence occurred in four of 744 patients in the axillary lymph node dissection group and seven of 681 in the axillary radiotherapy group. 5-year axillary recurrence was 0·43% (95% CI 0·00–0·92) after axillary lymph node dissection versus 1·19% (0·31–2·08) after axillary radiotherapy. The planned non-inferiority test was underpowered because of the low number of events. The one-sided 95% CI for the underpowered non-inferiority test on the hazard ratio was 0·00–5·27, with a non-inferiority margin of 2. Lymphoedema in the ipsilateral arm was noted significantly more often after axillary lymph node dissection than after axillary radiotherapy at 1 year, 3 years, and 5 years. Interpretation Axillary lymph node dissection and axillary radiotherapy after a positive sentinel node provide excellent and comparable axillary control for patients with T1–2 primary breast cancer and no palpable lymphadenopathy. Axillary radiotherapy results in significantly less morbidity. Funding EORTC Charitable Trust.

Sentinel lymph node biopsy is associated with reduced arm morbidity and better quality of life than standard axillary treatment and should be the treatment of choice for patients who have early-stage breast cancer with clinically negative nodes.

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Cancer Research UK, the National Health and Medical Research Council Australia, Sanofi-Aventis, and AstraZeneca.

This study is the first large prospective RCT of sentinel node biopsy (SNB) compared with standard axillary treatment (level I-III axillary lymph node dissection or four node sampling), which includes comprehensive and repeated quality of life (QOL) assessments over 18 months. Patients (n = 829) completed the Functional Assessment of Cancer Therapy - Breast (FACT-B+4) and the Spielberger State/Trait Anxiety Inventory (STAI) at baseline (pre-surgery) and at 1, 3, 6, 12, and 18 months post-surgery. There were significant differences between treatment groups favouring the SNB group throughout the 18 months assessment. Patients in the standard treatment group showed a greater decline in Trial Outcome Index (TOI) scores (physical well-being, functional well-being and breast cancer concerns subscales in FACT-B+4) and recovered more slowly than patients in the SNB group (p < 0.01). The change in total FACT-B+4 scores (measuring global QOL) closely resembled the TOI results. 18 months post-surgery approximately twice as many patients in the standard group compared with the SNB group reported substantial arm swelling (14% versus 7%) (p = 0.002) or numbness (19% versus 8.7%) (p < 0.001). Despite the uncertainty about undergoing a relatively new procedure and the possible need for further surgery, there was no evidence of increased anxiety amongst patients randomised to SNB (p > 0.05). For 6 months post-surgery younger patients reported less favourable QOL scores (p < 0.001) and greater levels of anxiety (p < 0.01). In view of the benefits regarding arm functioning and quality of life, the data from this randomised study support the use of SNB in patients with clinically node negative breast cancer.