Extension of ACOSOG Z0011 to breast cancer patients receiving mastectomy

Abstract

Background: The ACOSOG Z0011 trial resulted in de-escalation of axillary surgery in early-stage breast cancer patients with low volume sentinel lymph node {SLN) disease treated with breast conservative surgery and radiation therapy. The incidence of mastectomy among Chinese population remains high. It is of great clinical interest to evaluate the applicability of these findings in SLN-positive mastectomy patients. Methods: Retrospective analysis from a prospectively maintained database in a tertiary breast cancer centre in Hong Kong was performed from June 2014 to May 2019. All patients with clinical Tl or 2 invasive breast carcinoma, no palpable adenopathy, one or two positive SLNs on histological examination, and no prior neoadjuvant systemic treatment were recruited. Comparison was made between the mastectomy group and breast conservative treatment group of our cohort together with the sentinel alone arm in the ACOSOG Z0011 trial. Results: One hundred and seventy-one patients fulfilled the inclusion criteria, 112 patients with mastectomy and 59 with breast conservatiive treatment. Our mastectomy cohort had more T2 tumors (p=0.00002), higher incidence of lymphovascular invasion (p=0.000002) and SLN macrometastases (p=0.004) than the ACOSOG cohort. However, within our patient population, there was only a slight difference in the mean pathological size between mastectomy and breast conservative treatment arm (2.2cm versus 1.8cm; p=0.005). Other histopathological features were similar. Conclusion: This study demonstrates the comparable clinicopathological features among our SLN-positive mastectomy and breast conservative treatment patients in Hong Kong. This subgroup of low risk SLN-positive mastectomy patients may safely avoid completion axillary lymph node dissection (ALND).