Hypofractionated whole breast irradiation for patients with large breasts: a randomized trial comparing prone and supine positions.

Background And Purpose: Comparison of acute toxicity of whole-breast irradiation (WBI) in prone and supine positions.

Materials And Methods: This non-blinded, randomized, prospective, mono-centric trial was undertaken between December 29, 2010, and December 12, 2012. One hundred patients with large breasts were randomized between supine multi beam (MB) and prone tangential field (TF) intensity modulated radiotherapy (IMRT). Dose-volume parameters were assessed for the breast, heart, left anterior descending coronary artery (LAD), ipsilateral lung and contralateral breast. The primary endpoint was acute moist skin desquamation. Secondary endpoints were dermatitis, edema, pruritus and pain.

Results: Prone treatment resulted in: improved dose coverage (p<0.001); better homogeneity (p<0.001); less volumes of over-dosage (p=0.001); reduced acute skin desquamation (p<0.001); a 3-fold decrease of moist desquamation p=0.04 (chi-square), p=0.07 (Fisher's exact test)); lower incidence of dermatitis (p<0.001), edema (p=0.005), pruritus (p=0.06) and pain (p=0.06); 2- to 4-fold reduction of grades 2-3 toxicity; lower ipsilateral lung (p<0.001) and mean LAD (p=0.007) dose; lower, though statistically non-significant heart and maximum LAD.

Conclusions: This study provides level I evidence for replacing the supine standard treatment by prone IMRT for whole-breast irradiation in patients with large breasts. A confirmatory trial in a multi-institutional setting is warranted.