PL05 Presentation Time: 2:30 PM

Purpose

To report the 10-year late side-effects and cosmetic results of the GEC-ESTRO multicentric phase 3 accelerated partial breast irradiation (APBI) trial.

Materials and Methods

Women aged 40 years or older with stage 0-IIA breast cancer who underwent breast-conserving surgery (BCS) with clear resection margins were randomly assigned to receive either whole-breast irradiation (WBI) of 50 Gy with a tumor-bed boost of 10 Gy or APBI with interstitial brachytherapy. The non-inferiority of APBI in terms of local tumor control as primary end-point has been confirmed. Here, we report the secondary endpoints of late side-effects and cosmesis at 7.5 and 10 years of follow-up. This trial is registered with ClinicalTrials.gov number NCT00402519.

Results

Between 2004, and 2009, we randomly assigned 1328 women to receive either WBI (n=673) or APBI with interstitial brachytherapy (n=655); 1184 patients comprised the as-treated population and among these 10-year data on late side-effects and cosmetic results were available in 688 patients (313 in the WBI group and 375 in the APBI group). At 7.5 and 10 years 10 (2.7%) and 4 (1.3%) patients in the WBI group and 2 (0.4%) and 1 (0.3%) patients in the APBI group had grade 3 skin teleangiectasia (p=0.02 at 7.5 years and p=0.18 at 10 years). At 7.5 and 10 years 2 (0.5%) and 5 patients (1.6%) in the WBI group and 2 (0.4%) and 3 (0.8%) in the APBI group developed grade 3 late subcutaneous tissue toxicity (p=0.62 at 7.5 years and p=0.53 at 10 years). The incidence of grade 2-3 breast pain at 7.5 and 10 years was 1.6% and 1.0% after WBI versus 1.1% and 0.8% after APBI (p=0.39 at 7.5 years and p=0.93 at 10 years). At 7.5 years brachial lymphoedema occurred more frequently after WBI compared to APBI (5.4% vs 2.2%; p=0.03). At 7.5 and 10 years’ follow-up, according to the patients’ view, 31.9% and 33.8% of patients had excellent cosmetic results in the WBI group versus 44.3% and 45.0% of patients in the APBI group (p=0.001 at 7.5 years and p=0.002 at 10 years); when judged by the physicians, 31.7% and 33.2% of patients in the WBI group versus 40.0% and 40.0% of patients in the APBI group, had excellent cosmetic results, respectively (p=0.05 at 7.5 years and p=0.2 at 10 years).

Conclusions

Long-term toxicity profiles and cosmetic results were similar in patients treated with BCS followed by either APBI with interstitial brachytherapy or conventional WBI, with significantly fewer skin teleangiectasia and brachial lymphoedema accompanied with a slightly better cosmetic results after APBI with interstitial brachytherapy. These findings provide further clinical evidence for the routine use of sole interstitial multicatheter brachytherapy after BCS.