Oncologic outcomes after immediate breast reconstruction following mastectomy: comparison of implant and flap using propensity score matching

BACKGROUND: Although immediate breast reconstruction has been reported to be oncologically safe, no affirmative study comparing the two reconstruction methods exists. We investigated breast cancer recurrence rates in two breast reconstruction types; implant reconstruction and autologous flap reconstruction. METHODS: A retrospective cohort study was performed on propensity score-matched (for age, stage, estrogen receptor status) patients who underwent IBR after mastectomy at Seoul National University Hospital between 2010 and 2014. The main outcomes determined were locoregional recurrence-free interval (LRRFI) and disease-free interval (DFI). RESULTS: We analyzed 496 patients among 731 patients following propensity score matching (Median age 43, 247 implant reconstruction and 249 flap reconstruction). During median follow-up of 58.2 months, DFI was not different between the two groups at each tumor stage. However, flap reconstruction showed inferior DFI compared to implant reconstruction in patients with high histologic grade (p = 0.012), and with high Ki-67 (p = 0.028). Flap reconstruction was related to short DFI in multivariate analysis in aggressive tumor subsets. Short DFI after flap reconstruction in aggressive tumor cell phenotype was most evident in hormone positive/Her-2 negative cancer (p = 0.008). LRRFI, on the other hand, did not show difference according to reconstruction method regardless of tumor cell aggressiveness. CONCLUSION: Although there is no difference in cancer recurrence according to reconstruction method in general, flap-based reconstruction showed higher systemic recurrence associated with histologically aggressive tumors.