Surgery following neoadjuvant chemotherapy for HER2-positive locally advanced breast cancer. Time to reconsider the standard attitude

BackgroundWhile the addition of targeted therapy to neoadjuvant chemotherapy (NACT) dramatically increases the rate of pathological complete response in HER2-positive breast cancer, no reduction in the rate of mastectomy has been observed in randomised studies.MethodsA retrospective single centre analysis of all patients treated with anti HER2-based NACT for T2–4 breast cancer, focusing on patients treated with mastectomy.ResultsAmong 165 patients treated between June 2005 and July 2012, surgery was performed immediately post-NACT in 152 cases (92%). Breast-conserving surgery could be performed for 108 of the patients (71%), with a 4-year local relapse-free survival of 97%. A mastectomy was performed in two cases following patients’ wishes and in 37 cases based on pre-NACT findings (n = 18) or post-NACT outcomes (n = 19). For 21 out of the 37 cases, a good pathological response was observed, and multidisciplinary reanalysis suggests that breast-conserving surgery outright may have been sufficient for 12 patients. Finally, a salvage mastectomy based on post-lumpectomy pathological results was decided in five cases (11%). The 4-year metastasis-free survival was 84% for all patients operated on after NACT (n = 152).ConclusionsGiven the good efficacy of anti HER2-based NACT, breast-conserving surgery should be standard practice for most patients. Total mastectomy on the other hand should be restricted to a few patients, mainly those with positive margins on the lumpectomy specimen.