Session Item

In case of ipsilateral 2nd breast tumor event (2ndBTE), mastectomy or 2nd conservative treatment (2ndCT) combining lumpectomy plus accelerated partial breast re-irradiation (APBrI) represent the two salvage therapeutic options. We aimed to address the lack of evidence regarding 2ndCT prognostic factors in case of 2ndBTE.

The GEC-ESTRO prospective database was updated (7 hospitals/cancer centres from 6 European countries). In this study, patients (pts) with 2ndIBTE underwent 2ndCT with APBrI (multicatheter interstitial brachytherapy MIB). Pts were categorized using APBI and molecular classifications. Scoring systems were generated by combining APBI + Molecular classifications ([APBI/Mol] class.) and APBI + Molecular + Time interval between 1st/2nd lumpectomy ([APBI/Mol/TIS1S2] class.) (Fig. 1). Oncological outcome focused on 3rdIBTE (3rdIBTE-FS), regional relapse- (RRFS) and metastatic disease- (MD-FS) free survivals as well as disease-free (DFS), specific (SS) and overall (OS) survival. Prognostic factors for oncological outcome were explored by uni- and multivariate analysis. Late toxicity and cosmetic results were reported.

Figure 1:

etween 07/1994 and 01/2022, 508 pts experiencing a 2ndIBTE underwent a 2ndCT. Median age at the time of 2ndIBTE was 66 years [31–90], the median TIS1S2 was 152 months [12–437]. 2ndBTE occurred at distance from the primary tumor bed in 30%. Median tumor was 10 mm [7-15] while invasive ductal carcinoma was the most frequent histology (70%). Low-risk (APBI class.) and HR+/Her2- (molecular class.) pts were 313 (62%) and 346 (68%) respectively, while TIS1S2 was >60 months for 438 pts (86%). High-dose rate brachytherapy was used for 390 pts (77%). Endocrine therapy, chemotherapy and Trastuzumab were used in 369 pts (73%), 97 pts (19%) and 21 pts (4%) respectively.

With a MFU of 61 months [55–72], 5-y 3rdIBTE-FS, RRFS, MDFS, DFS, SS and OS were 96% [94–98], 98% [97–100], 93% [90–96], 89% [86–93], 95% [92–97] and 91% [88–94] respectively. In univariate analysis, tumor (>20 mm), [APBI/Mol] class. and [APBI/Mol/TIS1S2] class. were prognostic factors for all the oncological items while TIS1S2 (<36 m) was prognostic factor for RRFS, MDFS, SS and OS. In multivariate analysis, [APBI/Mol/TIS1S2] class. was the unique independent prognostic factor for all the oncological items but SS (trend) and OS (Fig. 2) .

404 late complications were observed in 298 pts (59%). Cutaneous and sub-cutaneous fibrosis were reported in 67.9%. The rate of G≥3 late toxicity was 12.1%. Cosmetic outcome was excellent and good in 36.8% and 30.3% respectively.

Figure 2:

In this updated analysis of its 2ndCT database, the GEC-ESTRO BCWG confirmed the excellent oncological results obtained after 2nd lumpectomy + MIB based APBrI for 2ndBTE. Furthermore, we provided new prognostic factors for discussing 2ndCT. [APBI/Mol/TIS1S2] class. appears to be an important tool for leading the making decision process.