Jean Michel Hannoun Levi, MD, PhD
SS 23 - Breast 3?- General
Purpose/Objective(s): Second conservative treatment (2ndCT) has emerged as an option for patients with second ipsilateral breast tumor event (2ndILBTE) after conserving surgery and whole breast irradiation. We aimed to address the lack of evidence regarding the 2ndILBTE treatment by comparing oncological outcomes after 2ndCT or salvage mastectomy (SM standard care).
Materials/Methods: Oncological outcomes after 2ndILBTE treatment were analyzed using a propensity-score matched cohort analysis study by patients diagnosed with a 2ndILBTE occurring between 01/2000 and 12/2014. Patient data were collected from 15 hospitals/cancer centers in 7 European countries. Patients were offered management with 2ndCT (lumpectomy + brachytherapy) or SM. For comparative analyses, propensity scores were calculated with logistic regression and multiple imputations (for missing data). Matching (1:1) was achieved using the nearest neighbor method with a caliper of 0.1 (including data related to 2ndILBTE: age, 1st/2ndILBTE time interval, tumor size, histological type and grade, hormonal receptor and Her2 status, chemotherapy, hormonal therapy and 2ndILBTE period). The primary endpoint was disease-free survival (DFS) from the salvage treatment date. Secondary endpoints were overall survival (OS), metastatis-free survival (MSF) and 3rdILBTE free survival.
Results: Among the 1329 analyzed patients (SM: 942/2ndCT: 387), 430 were matched by propensity score (SM: 215/2ndCT: 215). The median follow-up was 65 months [95%CI 58-78] and 68 months [95%CI 57-75] for SM and 2ndCT respectively (p=0.28). In the matched analyses, no differences in 5-year DFS were noted between SM and 2ndCT (78% [95%CI 71-84] vs 82% [76–89]; p=0.22). Similarly, no differences were noted in 5-year OS (90% [86–95] vs 86% [81–92]; p=0.85), MSF (92% [87–96] vs 94% [90–98]; p=0.75) and 3rdILBTE (94% [90–98] vs 98% [95–1]; p=0.17).
Conclusion: To our knowledge, this is the largest matched-analysis between SM and 2ndCT for 2ndILBTE. Compared to SM, 2ndCT including re-lumpectomy and salvage brachytherapy does not seem to be associated with measurable differences of DFS, OS, MSF or 3rdILBTE. Consequently, 2ndCT could be considered as a viable option for salvage treatment.
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