10-Year oncological outcome report after second conservative treatment for ipsilateral breast tumor event

To analyze long-term oncological outcome after 2nd conservative treatment (2^ndCT) for patients with ipsilateral 2nd ipsilateral breast tumor event (2^ndIBTE).

In this retrospective observational study (N°F20210402152843), patients with 2^ndIBTE underwent 2^ndCT (lumpectomy + tumor bed re-irradiation). 3^rdIBTE (3^rdIBTE-FS), regional relapse- (RRFS) and metastatic disease- (MD-FS) free survivals as well as disease-free (DFS), specific (SS) and overall (OS) survival were analyzed. Late toxicity was reported.

Between 09/2000 and 04/2022, 244 patients presented a 2^ndIBTE and underwent a 2^ndCT. Among them, 113 pts with a minimum follow-up of 60 months were analyzed. Median time interval between 1st and 2^ndIBTE was 13.5 years [2-35]. Median 2^ndIBTE age was 66.2 years [31-85]. 2^ndIBTE were adenocarcinomas (77 %). Tumor size was < 20 mm (86.7 %). 2^ndIBTE were grade 1/2 (75 %), with positive hormonal receptor (85 %) and clear surgical margins (no ink on tumor, 90.3 %). In the APBI classification, 21 pts were high-risk (18.6 %), while 77 % were Luminal A/BHer2-. With a MFU of 121.5 months [CI95% 111.7-129.6], 10-year 3^rdIBTE-FS was 89 % [83-96]. Then-year RRFS, MDFS, DFS, SS and OS were 94 % [89-100], 89 % [83-96], 78 % [70-87], 95 % [91-100] and 94 % [90 -99] respectively. In multivariate analysis, APBI classification (high-risk; HR2.66 [1.01-7.1], p = 0.049) and tumor size (≥20 mm; HR2.64 [1.02-6.8], p = 0.045) were considered independent prognostic factors for DFS.Ninety-seven late complications were observed (fibrosis 64 %) with 6.2 % G ≥ 3 late toxicity. Cosmetic outcome was excellent/good in 91.2 %.

With long follow-up, 2^ndIBTE managed with 2^ndCT allows second breast preservation without oncological outcome compromise and acceptable G ≥ 3 toxicity.