Locoregional recurrence after breast cancer surgery: A meta-analysis by molecular subtype.

Abstract

1053 Background: Molecular subtyping has confirmed that breast cancer comprises at least four genetically distinct entities, the phenotype of which influences both systemic and locoregional recurrence. The quantitative influence of subtype on ipsilateral locoregional recurrence (LRR) is unknown. The aim of this study was to systematically appraise the influence of breast cancer subtype on LRR following breast conserving therapy (BCT) and mastectomy. Methods: A comprehensive search for published studies that examined outcomes after BCT and/or mastectomy for patients according to breast cancer sub-type, was performed using Medline and cross referencing available data. Reviews of each study were conducted and data were extracted to perform meta-analysis. Primary outcome was LRR related to breast cancer subtype. Results: A total of 9,007 breast cancer patients who underwent either BCT (n=4790) or mastectomy (n=4217) were identified from studies examining LRR in relation to breast cancer subtype. Patients with luminal subtype tumor had lower risk of LRR than both triple-negative (OR=0.48; 95% CI 0.30−0.77) and Her2neu-overexpressing (OR= 0.27; 95% CI 0.18−0.39) tumours following BCT. Luminal tumours were also less likely to develop LRR than Her2neu-overexpressing (OR =0.7, 95% CI 0.52−0.95) or triple-negative tumours (OR=0.65, 95% CI=0.50−0.83) after mastectomy. Her2neu-overexpressing tumours have increased risk of LRR compared to triple-negative tumours (OR=1.7; CI 1.11−2.65) following BCT but there was no difference in LRR between Her2neu-overexpressing and triple-negative tumours following mastectomy (OR=0.9, 95% CI 0.64−1.28). Conclusions: Luminal tumors are associated with the lowest rates of LRR. Patients with triple negative and Her2/neu-overexpressing breast cancer subtypes are at increased risk of developing LRR following BCT or mastectomy. Breast cancer biologic subtype should be taken into account when considering local control of breast cancer and may be used to identify those at increased risk of local and regional recurrence who may benefit from more aggressive local treatment.