Second Conservative Treatment for Ipsilateral Breast Cancer Recurrence: First 10-Year Oncological Outcome Report

Abstract

<h3>Purpose/Objective(s)</h3> To analyze long-term oncological outcome after 2^nd conservative treatment (2^ndCT) for patients with ipsilateral 2^nd breast cancer event (2^ndBCE). <h3>Materials/Methods</h3> In this retrospective observational single institution study (Health-data-hub N°F20210402152843), patients with 2^ndBCE underwent 2^ndCT based on lumpectomy plus re-irradiation of the tumor bed with multicatheter interstitial brachytherapy (MIB). Oncological outcome was investigated based on 3^rd breast cancer event (3^rdBCE-FS) and metastatic disease (MD-FS) -free survivals as well as disease-free (DFS), cause-specific (CSS) and overall (OS) survival. Prognostic factors were analyzed. Late toxicity was reported. <h3>Results</h3> From 09/2000 to 05/2013, 113 pts presented a 2^ndBCE managed by 2^ndCT. Median relapse age was 64.8 years [31 - 85]. Median time interval between 1^st and 2^ndBCE was 162 months [24 - 420]. 2^ndIBE occurred in or close to the primary tumor bed in 47.8% and 31% respectively. Median 2^ndBCE size was 11.3 mm [1 - 40] while histological type was invasive ductal or lobular carcinoma in 77% and 13.3% respectively. Regarding APBI classification, patients were low, intermediate and high-risk in 37.2%, 44.4% and 18.6% respectively. Regarding molecular classification, patients were HR+/Her2-, Her2+ and triple negative in 88.8%, 5.1% and 6.1% respectively. New axillary lymph node dissection was performed in 5 pts (4.4%). Low and high-dose rate MIB were used for 27 (24%) and 86 pts (76%) respectively. Median HDR dose was 32 Gy [32 - 34]. Systemic treatments were hormonal (83.2%) and chemo- (13.3%) therapies. With a MFU of 121.5 months [48 – 129.6], 10-y 3^rdBCE-FS, MDFS, DFS, CSS and OS were 89% [83 - 96], 89% [83 - 96], 78% [70 - 87], 95% [91 - 100] and 94% [90 – 99] respectively. In univariate analysis, APBI classification was prognostic factor for 3^rdBCE (LR: 4.8%, IR: 12% and HR: 23.8%; p = 0.02) with a trend for DFS (LR: 19%, IR: 24% and HR: 42.9%; p = 0.055). Ninety-seven complications occurred in 73 pts (G1: 55.7%; G2: 38.1%; G3: 5.2%; G4: 1%) with cutaneous (36.1%) and sub-cutaneous (27.8%) fibrosis, telangiectasia (13.4%) and hyperpigmentation (4.1%). Cosmetic outcome was excellent, good, fair and poor in 70 pts (61.9%), 33 pts (29.2%), fair 9 pts (8%) and 1 pt (0.9%) respectively. <h3>Conclusion</h3> With long-term follow-up, 2^ndBCE managed with lumpectomy and tumor bed re-irradiation (MIB) allows the patient to avoid salvage mastectomy without compromise in oncological outcome. With about 5% of G≥3 late toxicity, final cosmetic outcome remains acceptable. Larger patient cohorts are needed to refine eligibility criteria for 2^ndCT while the place of systemic therapy remains under debate.