# ACOSOG Z0011 (Alliance)

Source: https://onco.cc/trials/acosog-z0011/  
OnCo record `acosog-z0011` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

Z0011 is the trial that stopped surgeons clearing the armpit when one or two sentinel nodes contain cancer. Ten years on, the women who kept their remaining nodes were no more likely to have died, and the cancer came back in the armpit in almost nobody.

## Summary

Z0011 enrolled 891 women from 1999 to 2004 at 115 academic and community centres with clinical T1 or T2 breast cancer, no palpable axillary nodes, and one or two sentinel nodes containing metastases. All had lumpectomy, planned tangential whole-breast irradiation and adjuvant systemic therapy; a third radiotherapy field aimed at the nodes was prohibited. They were randomised to sentinel node dissection alone or to completion axillary clearance. Overall survival was the primary endpoint with a non-inferiority margin of 1.3.

The trial first reported in 2005 with a median follow-up of 6.3 years. Longer follow-up mattered because most of the tumours were oestrogen receptor-positive and recur late. At a median 9.3 years, ten-year overall survival was 86.3 percent with sentinel node dissection alone and 83.6 percent with clearance (hazard ratio 0.85, one-sided 95 percent confidence interval 0 to 1.16, non-inferiority p=0.02). Ten-year disease-free survival was 80.2 against 78.2 percent (hazard ratio 0.85, 0.62 to 1.17, p=0.32). Between year five and year ten there was a single regional recurrence in the sentinel node arm and none in the clearance arm.

Two criticisms have followed the trial and both are fair. It closed early and is underpowered for a small survival difference. And every patient had whole-breast tangential radiotherapy, whose upper field edge treats part of the low axilla incidentally, so "no axillary treatment" is not quite what the experimental arm received. SENOMAC was designed to answer both, and reached the same conclusion in a population including mastectomy patients.

## Fields

- Kind: Trial
- Status: positive
- Last checked: 2026-09-25
- Also known as: Z0011; Z11; ACOSOG Z11
- Registry id: NCT00003855
- Phase: 3
- Setting: Clinical T1 or T2 invasive breast cancer, no palpable axillary nodes, one or two positive sentinel nodes, all having lumpectomy with tangential whole-breast irradiation and systemic therapy: sentinel node dissection alone against axillary clearance, with overall survival as the primary endpoint and a non-inferiority margin of 1.3
- Sponsor: Alliance for Clinical Trials in Oncology
- Enrolled: 891
- Result: Ten-year overall survival 86.3 percent with sentinel node dissection alone against 83.6 percent with axillary clearance (hazard ratio 0.85, non-inferiority p=0.02).
- Outcomes: Overall survival at 10 years: Sentinel node dissection alone 86.3% vs Axillary lymph node dissection 83.6%, HR 0.85; Disease-free survival at 10 years: Sentinel node dissection alone 80.2% vs Axillary lymph node dissection 78.2%, HR 0.85
- Replication: IBCSG 23-01 reached the same conclusion for micrometastases at ten years; AMAROS showed axillary radiotherapy is an equivalent alternative; SENOMAC extended the result to macrometastases, mastectomy and larger tumours in 2,540 patients.

## Sources

- ClinicalTrials.gov NCT00003855: https://clinicaltrials.gov/study/NCT00003855
- Z0011 ten-year overall survival (JAMA 2017): https://doi.org/10.1001/jama.2017.11470

## 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: [Alliance for Clinical Trials in Oncology](https://onco.cc/companies/alliance-oncology/)
- 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: [AMAROS (EORTC 10981-22023)](https://onco.cc/trials/amaros/), [IBCSG 23-01](https://onco.cc/trials/ibcsg-23-01/), [NSABP B-04](https://onco.cc/trials/nsabp-b04/), [NSABP B-32](https://onco.cc/trials/nsabp-b32/), [POSNOC](https://onco.cc/trials/posnoc/), [SENOMAC](https://onco.cc/trials/senomac/)

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