Vesprini et al. JAMA Oncol 2022 conducted a phase 3 randomized clinical trial in 5 centers across Canada from 2013 to 2018 to compare acute side effects of adjuvant breast radiation (to the breast alone, after breast conserving surgery) for women with a large breast size (bra band ≥40 inches and/or ≥D cup) in the prone vs. supine positions. From 2013 to June 2016, all 167 patients received 50 Gy in 25 fractions with or without boost (range, 10-16 Gy). After trial amendment in June 2016, a majority of the remaining patients (177 of 190) received hypofractionated radiation to 42.5 Gy in 16 fractions. The main outcome was desquamation.
Out of the 357 women included in the analysis, 182 (51.0%) were treated in the supine position and 175 (49.0%) were treated in prone position. There was a statistically significant difference in desquamation with more desquamation in patients treated in the supine position vs. prone (72 of 182 [39.6%] patients vs. 47 of 175 [26.9%] patients; OR, 1.78; 95% CI = 1.24-2.56; p = .002). This was confirmed on multivariable analysis, along with other independent factors: use of boost, extended fractionation, and bra size. No differences in quality of life, breast symptom, or pain scales were observed between arms. Extended fractionation was associated with increased toxic effects compared with hypofractionation, including desquamation and pain.
Clinical Pearl: A randomized clinical trial demonstrated that treatment in the prone position decreases desquamation in women with large breast size receiving adjuvant breast radiation. It also demonstrated increased toxic effects with a boost and conventional fractionation.
