GEC-ESTRO multicenter phase 3-trial: Accelerated partial breast irradiation with interstitial multicatheter brachytherapy versus external beam whole breast irradiation: Early toxicity and patient compliance.

BACKGROUND AND PURPOSE: To compare early side effects and patient compliance of accelerated partial breast irradiation (APBI) with multicatheter brachytherapy to external beam whole breast irradiation (WBI) in a low-risk group of patients with breast cancer.

MATERIAL AND METHODS: Between April 2004 and July 2009, 1328 patients with UICC stage 0-IIA breast cancer were randomized to receive WBI with 50Gy and a boost of 10Gy or APBI with either 32.0Gy/8 fractions, or 30.1Gy/7 fractions (HDR-brachytherapy), or 50Gy/0.60-0.80Gy per pulse (PDR-brachytherapy). This report focuses on early side-effects and patient compliance observed in 1186 analyzable patients. ClinicalTrials.gov identifier: NCT00402519.

RESULTS: Patient compliance was excellent in both arms. Both WBI and APBI were well tolerated with moderate early side-effects. No grade 4 toxicity had been observed. Grade 3 side effects were exclusively seen for early skin toxicity (radiation dermatitis) with 7% vs. 0.2% (p<0.0001), and breast infection with 0% vs. 0.2% (p=n.s.) for patients treated with WBI and APBI. The incidence of grades 1-2 early side effects for WBI and APBI was 86% vs. 21% (p<0.0001) for skin toxicity, 2% vs. 20% (p<0.0001) for mild hematoma, and 2% vs. 5% (p=0.01) for mild breast infection rates, respectively. No differences had been found regarding grades 1-2 early breast pain (26% vs. 29%, p=0.23).

CONCLUSIONS: APBI with interstitial multicatheter brachytherapy was tolerated very well and dramatically reduced early skin toxicity in comparison to standard WBI.