Analyzing non-sentinel axillary metastases in patients with T3–T4 cN0 early breast cancer and tumor-involved sentinel lymph nodes undergoing breast-conserving therapy or mastectomy

Purpose!#!In the ACOSOG Z0011 trial, completing axillary lymph node dissection (cALND) did not benefit patients with T1-T2 cN0 early breast cancer and 1-2 positive sentinel lymph nodes (SLN) undergoing breast-conserving surgery (BCT). This paper reports cALND rates in the clinical routine for patients who had higher (T3-T4) tumor stages and/or underwent mastectomy but otherwise met the ACOSOG Z0011 eligibility criteria. Aim of this study is to determine cALND time trends and non-sentinel axillary metastases (NSAM) rates to estimate occult axillary tumor burden.!##!Methods!#!Data were included from patients treated in 179 German breast cancer centers between 2008 and 2015. Time-trend rates were analyzed for cALND of patients with T3-T4 tumors separated for BCT and mastectomy and regarding presence of axillary macrometastases or micrometastases.!##!Results!#!Data were available for 188,909 patients, of whom 19,009 were identified with 1-2 positive SLN. Those 19,009 patients were separated into 4 cohorts: (1) Patients with T1-T2 tumors receiving BCT (ACOSOG Z0011 eligible; n = 13,741), (2) T1-T2 with mastectomy (n = 4093), (3) T3-T4 with BCT (n = 269), (4) T3-T4 with mastectomy (n = 906). Among patients with T3-T4 tumors, cALND rates declined from 2008 to 2015: from 88.2 to 62.6% for patients receiving mastectomy and from 96.6 to 58.1% in patients receiving BCT. Overall rates for any NSAM after cALND for cohorts 1-4 were 33.4%, 42.3%, 46.9%, 58.8%, respectively.!##!Conclusions!#!The cALND rates have decreased substantially in routine care in patients with 'extended' ACOSOG Z0011 eligibility criteria. Axillary tumor burden is higher in these patients than in the ACOSOG Z0011 trial