Which patients with sentinel node-positive breast cancer after breast conservation still receive completion axillary lymph node dissection in routine clinical practice?

PURPOSE: In the American College of Surgeons Oncology Group (ACOSOG) Z0011 trial, patients with 1 or 2 tumour-involved sentinel lymph nodes (SLNs) gained no benefit from completion axillary lymph dissection (cALND). We examined implementation of evidence from this trial into routine clinical management.

METHODS: Data were included from patients diagnosed with primary breast cancer in German breast cancer units between 2008 and 2015 and analysed retrospectively from a prospective maintained database. Descriptive analyses assessed time-trend changes in axillary surgery. Factors associated with cALND in patients with 1 or 2 positive SLNs were identified using multivariable logistic regression analysis.

RESULTS: Overall, 179 breast cancer units provided data for 188,909 patients, of whom 13,741 (7.3%) had pT1/2cN0M0 invasive breast cancer with 1 or 2 tumour-involved SLNs and underwent breast-conserving surgery and adjuvant radiotherapy. cALND use decreased from 94.6% in 2008 to 46.9% in 2015 (p < 0.001). In multivariable analyses, the following factors were associated with cALND: fewer removed SLNs; two tumour-affected SLNs; younger age; lower annual case volume per hospital; higher tumour grade and lymphovascular invasion. No statistically significant influence was detected for hormone receptor or HER2 status.

CONCLUSION: In our cohort, 7.3% of patients with primary breast cancer met the ACOSOG Z0011 inclusion criteria and could potentially have been spared the morbidity of cALND. cALND tended to be performed in patients with a higher axillary tumour burden. This study shows a shift towards less extensive axillary surgery through rapid implementation of new clinical trial evidence into routine clinical practice.