Impact of bra application in breast cancer radiotherapy: A pilot prospective randomized trial.

Abstract

This prospective, randomized clinical trial evaluated the effects of bra-wearing during radiotherapy on breast-shape reproducibility, dosimetry, and treatment toxicities in patients with breast cancer. Thirty-eight patients with breast cancer who underwent breast-conserving surgery were randomly assigned to bra-wearing or non-wearing groups during radiotherapy. Breast-shape reproducibility was assessed using daily cone-beam computed tomography (CBCT). The primary outcome was breast-shape reproducibility, evaluated by the nipple-to-pectoral muscle distance (ΔNPD) and mean surface distance (MSD), comparing daily CBCT to planning CT. We calculated the mean root-mean-squared error (ε), systematic error (Σ), and random error (σ). Secondary outcomes included dosimetric parameters and acute/subacute toxicities. ΔNPD ε (1.0 mm vs 3.8 mm, P < 0.001), Σ (0.6 mm vs 3.6 mm, P < 0.001), and σ (0.8 mm vs 2.2 mm, P < 0.001) were significantly smaller in the bra-wearing group. For larger breasts (cup sizes C-D), MSD ε was significantly smaller in the bra-wearing group (1.1 mm vs. 2.1 mm, P = 0.006), but not for smaller breasts. The absolute ΔNPD exceeded 3 mm in 0.4 % of CBCT scans in the bra-wearing group and 48.1 % in the non-wearing group (P < 0.001). Absolute MSD exceeded 3 mm in 2.1 % and 10.0 % of scans in the bra-wearing and non-wearing groups, respectively (P < 0.001). No significant differences were observed in lung and heart dosimetric outcomes between groups. Grade 2 or higher toxicities were minimal in both groups. The use of a bra during radiotherapy enhances breast-shape reproducibility, particularly in patients with larger breasts, without increasing treatment toxicities. NCT06178861.