Résumé
In ductal carcinoma in situ, whole breast radiation therapy (WBRT) reduces local recurrence rates, but ipsilateral breast events at 10 years were observed in 15% to 19% of 50-year-old patients. The BONBIS trial (NCT00907868) assessed the effect of an additional localized radiation boost on local recurrence-free survival (primary endpoint).
This large multicenter (n = 53), randomized, open-label phase 3 trial was conducted from November 2008 to July 2014. In total, 2004 patients with complete ductal carcinoma in situ resection underwent postsurgery WBRT followed or not by a 16-Gy boost in the tumor bed. Only late radiation therapy-induced toxicity occurrence (National Cancer Institute Common Terminology Criteria for Adverse Events v3.0), health-related quality of life European Organisation for Research and Treatment Of Cancer (EORTC) Quality of life Cancer Patients (QLQ-C30) v3.0 and EORTC Quality of life Breast Cancer Patients (QLQ-BR23), and potential predictive factors of breast subcutaneous fibrosis (BSCF) (ie, secondary endpoints) will be reported here because the primary endpoint has not been reached yet.
After a median follow-up of 66.9 months (95% CI, 65.1-67.8), grade ≥2 BSCF was observed in 4.9% of patients (7.0% in the WBRT + boost vs 2.8% in the WBRT arm; P < .001). Grade ≥2 acute and late toxicities were positively correlated (P = .005). Grade ≥2 BSCF was correlated with the boost (odds ratio = 2.6; 95% CI, 1.62-4.30) and breast clinical target volume ≥500 cm3 (odds ratio = 1.6; 95% CI, 1.01-2.51). Among the QLQ-C30 and QLQ-BR23 domain and symptom scores, only the breast symptom scores exhibited an arm-by-time interaction effect (P = .001) with a greater long-term breast symptom experience in the WBRT + boost arm. Time to first deterioration analysis showed a statically significant deterioration for body image in the WBRT + boost arm (hazard ratio = 1.19; 95% CI, 1.00-1.41).
The boost significantly increased grade ≥2 BSCF occurrence and persistent breast symptoms.