Prone versus supine position for adjuvant breast radiotherapy: a prospective study in patients with pendulous breasts

Abstract

PurposeTo analyze dosimetric parameters of patients receiving adjuvant breast radiotherapy (RT) in the prone versus supine position.Methods and materialsForty-one out of 55 patients with pendulous breasts and candidates for adjuvant RT were enrolled in the study after informed consent. They underwent computed tomography (CT)-simulation in both prone and supine position. Target and non target volumes were outlined on CT images. Prescribed dose was 50 Gy delivered by two tangential photon fields followed by 10 Gy electron boost. Target coverage and dose homogeneity to clinical target volume (CTV) and planning target volume (PTV) were assessed by V95, V105 and V107 and dose to lung, heart and left anterior descending coronary artery (LAD) by V5, V10, V20, and mean and maximum dose. Data were analyzed by Student’s t-test.ResultsCTV and PTV coverage was significantly better in supine than in prone position. Lung V5, V10, and V20 were significantly lower in prone than in supine position. Heart V5, V10, V20, and LAD mean and maximum dose, in the 17 patients with left breast tumor, were lower in prone than in supine position, but without statistical significance. Based on treatment planning data and on treatment feasibility, 29/41 patients (70.7%) were treated in prone position. Acute and late toxicities of patients treated in prone and in supine position were not statistically different.ConclusionProne position is a favorable alternative for irradiation of mammary gland in patients with pendulous breasts and in our series was adopted in 71% of the cases.

The UK HeartSpare Study (Stage IB): Randomised comparison of a voluntary breath-hold technique and prone radiotherapy after breast conserving surgery

“…The prone mean heart NTD mean and mean LAD max doses were lower than those seen in standard free-breathing left breast radiotherapy [20], although confidence intervals overlap. Prone cardiac doses in this study were generally lower than reported in other studies comparing prone and supine treatments [11,21,22]. In keeping with the literature, mean lung doses were also significantly lower with prone treatment than supine treatment [9,11,23].…”

“…A possible reason for this is that MLC use or alteration of beam angles to avoid cardiac tissue is likely to result in relatively less WBCTV coverage compromise in larger-vs smaller-breasted women. Contrary to other published reports [21,24,25], this study demonstrates that it is possible to achieve comparable dose homogeneity for both techniques, but that to do so, more segments are required for supine treatment.…”

The impact of imaging modality (CT vs MRI) and patient position (supine vs prone) on tangential whole breast radiation therapy planning

“…This is the first study to analyse target and OAR dose compliance differences due to imaging modality (CT vs MRI) for target volume determination, in both supine and prone positions, although several groups have examined differences in supine and prone positioning for WB radiotherapy (Table 6) [13][14][15][16][17][18][19][20][21][22][23][24][25][26].…”

“…Some authors report that prone positioning is better at heart dose and/or volume sparing than supine [15-17, 20, 23]. Some have reported no significant difference in heart dose between prone and supine positions [19,22]. One group identified a significant benefit of prone positioning on heart doses for women where the WB_CTV exceeded 1000 cm 3 for WB radiotherapy [18].…”

“…Several groups have examined differences in supine and prone positioning for WB radiotherapy [13][14][15][16][17][18][19][20][21][22][23][24], however few groups have examined the impact of imaging modality on breast radiotherapy planning. Mast et al observed that the mean volume of delineated glandular breast tissue was significantly larger on CT compared to that volumed on co-registered CT-MRI breast radiotherapy planning images acquired with the patient in the supine position [25].…”