Multifocality in ipsilateral breast tumor recurrence - A study in ablative specimens

Background: The incidence and clinical significance of multifocality in ipsilateral breast tumor recurrence (IBTR) after breast-conserving therapy (BCT) are unclear. With growing interest in repeat BCT, this information has become of importance. This study aimed to gain insight in the incidence of multifocality in IBTR, to identify patient- and tumor-related predicting factors and to investigate the prognostic significance of multifocality. Methods: Two hundred and fifteen patients were included in this analysis. All had an IBTR after BCT and were treated by salvage mastectomy and appropriate adjuvant therapy. Predictive tumor- and patient-related factors for multifocality in IBTR were identified using X2 test and univariate logistic regression analyses. Prognostic outcomes were calculated using Kaplan Meier analysis and compared using the log rank test. Results: Multifocality was present in 50 (22.9%) of IBTR mastectomy specimens. Axillary positivity in IBTR was significantly associated with multifocality in IBTR. Chest wall re-recurrences occurred more often after multifocal IBTR (14% versus 7% after unifocal IBTR, p = 0.120). Regional re-recurrences did not differ significantly between unifocal and multifocal IBTR (8% vs. 6%, p = 0.773). Distant metastasis after salvage surgery occurred more frequently after multifocal IBTR (15% vs. 24%, p = 0.122). Overall survival was 132 months after unifocal IBTR and 112 months after multifocal IBTR (p = 0.197). Conclusion: The prevalence of multifocality in IBTR is higher than in primary breast cancer. Axillary positivity in IBTR was associated with a multifocal IBTR. Chest wall re-recurrences and distant metastasis were, although not statistically significant, more prevalent after multifocal IBTR. (C) 2020 Elsevier Ltd, BASO similar to The Association for Cancer Surgery, and the European Society of Surgical Oncology. All rights reserved.