Prone versus supine free-breathing for right-sided whole breast radiotherapy

Abstract

Prone setup has been advocated to improve organ sparing in whole breast radiotherapy without impairing breast coverage. We evaluate the dosimetric advantage of prone setup for the right breast and look for predictors of the gain. Right breast cancer patients treated in 2010–2013 who had a dual supine and prone planning were retrospectively identified. A penalty score was computed from the mean absolute dose deviation to heart, lungs, breasts, and tumor bed for each patient's supine and prone plan. Dosimetric advantage of prone was assessed by the reduction of penalty score from supine to prone. The effect of patients' characteristics on the reduction of penalty was analyzed using robust linear regression. A total of 146 patients with right breast dual plans were identified. Prone compared to supine reduced the penalty score in 119 patients (81.5%). Lung doses were reduced by 70.8%, from 4.8 Gy supine to 1.4 Gy prone. Among patient's characteristics, the only significant predictors were the breast volumes, but no cutoff could identify when prone would be less advantageous than supine. Prone was associated with a dosimetric advantage in most patients. It sets a benchmark of achievable lung dose reduction.Trial registration: ClinicalTrials.gov NCT02237469, HUGProne, September 11, 2014, retrospectively registered.

Four irradiation and three positioning techniques for whole‐breast radiotherapy: Is sophisticated always better?

“…These acute and late side effects are particularly important for early‐stage and young patients who have a high probability of long‐term breast cancer survival, 4 and for patients with pulmonary risk factors 31,41 . To enable lung sparing, the added value of the prone dive position is widely acknowledged 4,19,20,30,37,40,42 . Significant lung sparing was also attributed to the prone crawl position in WBI + LNI studies, with mean lung dose reductions of up to 50% compared to supine positioning 11,14 .…”

Prone Whole-Breast Radiotherapy—Better Than Supine?

“…A more detailed picture of the effect of these findings is limited by the absence of dosimetric analysis of the left anterior descending (LAD) coronary artery, whole heart, and ipsilateral lung dose, as there may be subgroups of patients for whom prone positioning would be more (or less) advantageous, particularly as it relates to laterality and breast pendulousness. With prone setup, studies uniformly demonstrate considerable reduction in ipsilateral lung dose regardless of laterality (up to 94% of patients with left-sided cancer and 98% of patients with right-sided cancer) . However, prone positioning pulls the heart anteriorly toward the chest wall and closer to the beam edge for left-sided cancers.…”

“…While comfort and positioning are improved with commercially available devices, patients with reduced mobility or morbid obesity may have challenges. Approximately half (53%) of patients reported a preference for supine positioning after experiencing both setups, while only 22% to 30% preferred prone . Additionally, studies suggest a 1.2- to 1.6-cm expansion (clinical target volume to planning target volume) to account for intrafraction and interfraction motion and larger setup uncertainty, markedly larger than for supine setup.…”

“…Based on the results from Vesprini et al and studies comparing dosimetric differences between prone and supine positioning, which patients benefit most and least from prone positioning? For patients with large breast size and right-sided breast cancer, prone positioning results in less moist desquamation and lower lung dose, and appears to be an excellent option. Prone positioning also results in decreased late changes in skin pigmentation among women with large breast size, regardless of laterality.…”

“…For patients with large breast size and left-sided breast cancer, while prone positioning does reduce the incidence of desquamation, radiation exposure of the heart may potentially be higher than supine-DIBH for some patients, suggesting the need for thoughtful attention to identify which patients may be better suited for supine-DIBH. For women with smaller breast volume, prone positioning remains a good option for right-sided cancer but may be associated with higher heart dose for patients with left-sided cancer . Studies evaluating moist desquamation with prone positioning selected patients with large breast size, resulting in a lack of evidence regarding the incidence of desquamation with prone positioning among women with smaller breast size.…”