# NSABP B-32

Source: https://onco.cc/trials/nsabp-b32/  
OnCo record `nsabp-b32` (Trial). Data CC BY-NC 4.0, attribute "Data from OnCo (onco.cc)"; commercial use needs a licence.

## TL;DR

The trial that made it safe to take one or two lymph nodes instead of twenty. Where the first node the cancer drains to is clear, clearing the rest of the armpit adds nothing to survival and adds a lifetime of arm swelling risk.

## Summary

NSABP B-32 randomised 5,611 women with clinically node-negative invasive breast cancer at 80 centres in the United States and Canada between 1999 and 2004. Group 1 had sentinel node resection followed by axillary clearance whatever the sentinel node showed; group 2 had sentinel node resection alone, with clearance only if the sentinel node contained cancer. Mapping used both blue dye and a radioactive tracer. The primary endpoint was overall survival among the 3,989 patients whose sentinel nodes were negative.

At a mean 95.6 months, 309 deaths had occurred among the 3,986 sentinel node-negative patients with follow-up: 140 of 1,975 in group 1 and 169 of 2,011 in group 2. The unadjusted hazard ratio for overall survival was 1.20 (95 percent confidence interval 0.96 to 1.50, p=0.12), with eight-year estimates of 91.8 against 90.3 percent. Disease-free survival gave a hazard ratio of 1.05 (0.90 to 1.22, p=0.54), with eight-year estimates of 82.4 against 81.5 percent. Regional node recurrence as a first event occurred in eight patients in group 1 and fourteen in group 2 (p=0.22).

B-32 is the largest trial of the sentinel node concept ever run, and its conclusion is unqualified: when the sentinel node is negative, sentinel node surgery alone is appropriate, safe and effective.

## Fields

- Kind: Trial
- Status: positive
- Last checked: 2026-09-25
- Also known as: National Surgical Adjuvant Breast and Bowel Project B-32; NSABP B32
- Registry id: NCT00003830
- Phase: 3
- Setting: Invasive breast cancer with clinically negative nodes: sentinel node resection followed by axillary clearance in every patient, against sentinel node resection with clearance only if the sentinel node was positive, with overall survival as the primary endpoint
- Sponsor: National Surgical Adjuvant Breast and Bowel Project
- Enrolled: 5611
- Result: Eight-year overall survival 90.3 percent with sentinel node biopsy alone against 91.8 percent with added clearance (hazard ratio 1.20, 0.96 to 1.50, p=0.12); regional recurrence 14 against 8 events.
- Outcomes: Overall survival at 8 years (sentinel node-negative patients): Sentinel node resection alone 90.3% vs Sentinel node resection plus axillary clearance 91.8%, HR 1.2; Disease-free survival at 8 years: Sentinel node resection alone 81.5% vs Sentinel node resection plus axillary clearance 82.4%, HR 1.05
- Replication: ALMANAC, run in parallel in the United Kingdom, measured the morbidity side of the same question and found lymphoedema and sensory loss cut to about a third.

## Sources

- ClinicalTrials.gov NCT00003830: https://clinicaltrials.gov/study/NCT00003830
- NSABP B-32 overall survival (Lancet Oncology 2010): https://doi.org/10.1016/S1470-2045(10)70207-2

## 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: [Sentinel lymph node biopsy](https://onco.cc/technologies/sentinel-node/)
- companies: [NRG Oncology](https://onco.cc/companies/nrg-oncology/), [NSABP Foundation](https://onco.cc/companies/nsabp-foundation/)
- 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/), [ALMANAC (Axillary Lymphatic Mapping Against Nodal Axillary Clearance)](https://onco.cc/trials/almanac/), [INSEMA (Intergroup Sentinel Mamma)](https://onco.cc/trials/insema/), [NSABP B-04](https://onco.cc/trials/nsabp-b04/), [SOUND (Sentinel Node vs Observation After Axillary Ultra-Sound)](https://onco.cc/trials/sound/)

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