In a Canadian phase III trial reported in JAMA Oncology, Vesprini et al found that receipt of adjuvant breast radiotherapy in the supine position was associated with increased risk of moist desquamation of skin vs receipt in the prone position among large-breasted women with breast cancer.
In the single-blind multicenter trial, 357 evaluable women with large breast size—defined as bra band ≥ 40 inches or ≥ D cup size—were randomly assigned between April 2013 and June 2016 to receive radiotherapy in the supine (n = 182) or prone position (n = 175). The primary outcome measure was moist desquamation. From April 2013 through June 2016, all patients (n = 167) received radiotherapy at 50 Gy in 25 fractions (extended fractionation) with or without boost (range = 10–16 Gy). After amendment in June 2016, 177 of 190 patients (93.2%) received a hypofractionation regimen of 42.5 Gy in 16 fractions.
Desquamation of any grade occurred in 72 (39.6%) of 182 patients in the supine group vs 47 (26.9%) of 175 in the prone group (odds ratio [OR] = 1.78, 95% confidence interval [CI] = 1.242.56, P = .002). Grade 3 desquamation occurred in 15.4% vs 8.0% (OR = 2.09, 95% CI = 1.62–2.69, P < .001).
No significant differences between the supine and prone groups were observed for grade ≥ 2 pain (7.7% vs 5.1%; OR = 1.54, 95% CI = 0.52–4.58, P = .44), grade ≥ 2 erythema (80.8% vs 77.1%; OR = 1.24, 95% CI = 0.45–3.37, P = .67), or grade ≥ 1 edema (46.3 vs 48.0%; OR = 0.85, 95% CI = 0.56–1.23, P = .75).
On multivariate analysis, supine position was significantly associated with risk of desquamation (OR = 1.99, 95% CI = 1.48–2.65, P < .001). Other factors significantly associated with risk of desquamation were use of radiotherapy boost (OR = 2.71, 95% CI = 1.95–3.77, P < .001), extended fractionation (OR = 2.85, 95% CI = 1.41–5.79, P = .004), and bra band size > 40 inches (OR = 2.59, 95% CI = 1.51–4.36, P < .001).
The investigators concluded, “This randomized clinical trial confirms that treatment in the prone position decreases desquamation in women with large breast size receiving adjuvant radiotherapy. It also shows increased toxic effects using an radiotherapy boost and conventional fractionation.”
Danny Vesprini, MD, MSc, of Odette Cancer Centre, Sunnybrook Health Sciences Centre, Toronto, is the corresponding author for the JAMA Oncology article.
Disclosure: The study was supported by the Canadian Cancer Society. For full disclosures of the study authors, visit jamanetwork.com.The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.