Non-sentinel axillary tumor burden applying the ACOSOG Z0011 eligibility criteria – clinical results from 179 breast centers in Germany 2008 – 2015

Objectives:

In the ACOSOG Z0011 trial patients with primary breast cancer (BC) and 1 – 2 tumor-involved sentinel lymph nodes (SLN) undergoing breast-conserving surgery gained no benefit from completing axillary lymph node dissection (cALND). Here we report cALND rates for patients treated in clinical routine eligible for the ACOSOG Z0011 criteria. Further, these patients with cALND were analyzed concerning the number of non-sentinel metastases (NSM) to estimate axillary tumor burden which would have been potentially left behind.

Material and methods:

Data were retrospectively analyzed from patients diagnosed in n = 179 German breast units between 2008 – 2015. Time-trend rates for cALND regarding presence of axillary macro- or micrometastases were evaluated. Descriptive analyses assessed NSM in dependence from the combination of total number of removed and tumor involved SLNs, tumor stage (pT1 – 2) and immunohistochemical subtype. Factors associated with NSM were identified using multivariable logistic regression.

Results:

Overall, data for 188,909 patients were provided, of whom 13,741 (7.3%) were identified as eligible for the ACOSOG Z0011 criteria. For this group cALND rate declined from over 95% (macrometastases) and 85% (micrometastases) in 2010 to less than 50% and 5% in 2015, respectively. In total n = 9773 still received cALND where in 33.3% NSM were found. NSM rate were for pN(1/1sn) 38.3%, pN(1/2sn) 28.6% and pN(2/2sn) 50.9% whereas regarding subtypes HER2-positive showed highest (41.6%) and Luminal-A lowest (29.4%) rates.

Conclusions:

Rate of cALND for ACOSOG Z0011 eligible patients has decreased significantly in routine care in our nationwide cohort. Our data reveal relatively high prevalence of additional axillary NSM tumor burden.