LAUSR

We appreciate the letter to the editor from Drs Fitzal, Helgott, Moinfar and Gnant regarding our editorial on axillary staging in women over 70 years of age with endocrine-responsive breast cancer. The data presented from the Austrian group support that tumor size is a helpful adjunct when selecting which patients should undergo sentinel lymph node surgery for staging and which patients can avoid surgical axillary staging. The Austrian group reviewed 1400 women aged 70 ? years with endocrine-responsive breast cancer. Compared with the rates of nodal positivity we found in the National Cancer Database (NCDB) and the Mayo cohort, the rate in the Austrian cohort of women was significantly higher at 32%. As the studied time frames differed, with the Austrian group including cases from 1999 to 2014, the NCDB cohort including cases from 2004 to 2013, and Mayo including cases from 2008 to 2016, this may in part explain the observed differences. At Mayo Clinic, Rochester, in that time frame, routine axillary ultrasound was used in all cases with invasive breast cancer, impacting how we identified cN0 patients for our cohort, and this may in part account for the difference in nodal positivity rates. The Austrian group reports that since the vast majority of patients with node-positive disease had tumors[ 1 cm in size, axillary staging can be omitted in women with T1a and T1b tumors. They did not find that grade helped in defining a subset of women at low risk of nodal involvement. However, the proportion of cases of endocrineresponsive breast cancer in women aged 70 ? years that is T1a/b may be a relatively small group of women to whom we may apply the Society of Surgical Oncology (SSO) Choosing Wisely guidelines. With Institutional Review Board approval, review of the Mayo cohort of 667 women aged 70 ? years with hormone receptor-positive disease found that with increasing T stage, there was a stepwise increase in rates of nodal positivity, as shown in Table 1, and, consistent with the Austrian data, the rate of nodal positivity was low in T1mic/a/b (\ 10%). Additionally, when looking at grade, the rate of nodal positivity was significantly higher (p = 0.001) for grade 2 tumors (19.3%) compared with grade 1 tumors (10.1%), with these two groups accounting for the majority (91%) of patients. The group of grade 3 tumors had a similar rate of nodal positivity to that seen in the group with grade 1 tumors (11.3%), however we were limited by the small sample size in this group. Society of Surgical Oncology 2017