# AMAROS (EORTC 10981-22023)

Source: https://onco.cc/trials/amaros/  
OnCo record `amaros` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

AMAROS asked whether radiotherapy could replace surgery in an armpit known to contain cancer. It can: the cancer came back in the armpit in about one woman in a hundred either way, but arm swelling was half as common after radiotherapy.

## Summary

AMAROS screened 4,806 patients with clinical T1 or T2 node-negative breast cancer by sentinel node biopsy and randomised the 1,425 who proved node-positive to axillary clearance (744) or axillary radiotherapy (681). The pre-planned ten-year analysis reported in 2023.

By intention to treat, the ten-year cumulative incidence of axillary recurrence was 0.93 percent after clearance (seven events) and 1.82 percent after radiotherapy (eleven events), a hazard ratio of 1.71 (95 percent confidence interval 0.67 to 4.39): both figures are very low, and the confidence interval is wide because the events are so few. There was no difference in overall survival (hazard ratio 1.17, 0.89 to 1.52) or disease-free survival (1.19, 0.97 to 1.46).

The reason to prefer radiotherapy is the arm. In the updated five-year analysis, lymphoedema occurred in 24.5 percent after clearance and 11.9 percent after radiotherapy (p<0.001), while quality-of-life scales did not differ. One finding cuts the other way and is reported as exploratory: the ten-year cumulative incidence of second primary cancers was 12.1 percent after radiotherapy and 8.3 percent after clearance.

The trial's own conclusion is that axillary radiotherapy is preferred over clearance for a patient with a positive sentinel node and T1 or T2 disease. In England, NICE NG101 recommendation 1.4.12 offers either.

## Fields

- Kind: Trial
- Status: positive
- Last checked: 2026-09-25
- Also known as: EORTC 10981-22023; After Mapping of the Axilla: Radiotherapy Or Surgery
- Registry id: NCT00014612
- Phase: 3
- Setting: Clinical T1 or T2 node-negative breast cancer with a positive sentinel node: axillary clearance against axillary radiotherapy, with the axillary recurrence rate as the endpoint and a non-inferiority design
- Sponsor: European Organisation for Research and Treatment of Cancer
- Enrolled: 1425
- Result: Ten-year axillary recurrence 1.82 percent after radiotherapy against 0.93 percent after clearance, with no difference in survival and lymphoedema halved (11.9 against 24.5 percent at five years).
- Outcomes: Cumulative incidence of axillary recurrence at 10 years: Axillary radiotherapy 1.82% vs Axillary lymph node dissection 0.93%, HR 1.71; Lymphoedema at 5 years: Axillary radiotherapy 11.9% vs Axillary lymph node dissection 24.5%; Second primary cancers at 10 years (exploratory): Axillary radiotherapy 12.1% vs Axillary lymph node dissection 8.3%
- Replication: Z0011 and SENOMAC showed that in much of this population neither treatment is needed; AMAROS remains the evidence for what to do when the axilla does have to be treated.

## Sources

- ClinicalTrials.gov NCT00014612: https://clinicaltrials.gov/study/NCT00014612
- AMAROS ten-year results (Journal of Clinical Oncology 2023): https://doi.org/10.1200/JCO.22.01565

## Connected records

- cancers: [Breast cancer (all types)](https://onco.cc/cancers/breast-cancer/), [HER2-positive breast cancer](https://onco.cc/cancers/breast-her2-positive/), [HR-positive / HER2-negative breast cancer](https://onco.cc/cancers/breast-hr-positive/), [Triple-negative breast cancer (TNBC)](https://onco.cc/cancers/tnbc/)
- technologies: [IMRT / IGRT (modern external beam)](https://onco.cc/technologies/imrt-igrt/), [Sentinel lymph node biopsy](https://onco.cc/technologies/sentinel-node/)
- companies: [EORTC](https://onco.cc/companies/curie-nki-eortc/)
- terms: [Doing less to the armpit](https://onco.cc/terms/axillary-surgery-de-escalation/), [Lymphadenectomy (lymph node dissection)](https://onco.cc/terms/lymphadenectomy/), [Lymphoedema after breast cancer treatment](https://onco.cc/terms/breast-cancer-related-lymphoedema/), [Sentinel node biopsy](https://onco.cc/terms/sentinel-lymph-node-biopsy/)
- trials: [ACOSOG Z0011 (Alliance)](https://onco.cc/trials/acosog-z0011/), [POSNOC](https://onco.cc/trials/posnoc/), [SENOMAC](https://onco.cc/trials/senomac/)

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