Key result
Deep breath-hold and prone positioning linked to ~44% lower mean heart dose vs supine free breathing.
Why the study?
Do deep inspirational breath-hold in a supine position and free breathing in a prone position reduce radiation doses to cardiac structures compared to free breathing in a supine position in patients with left-sided early-stage breast cancer?
Observational (n=33)
Do deep inspirational breath-hold in a supine position and free breathing in a prone position reduce radiation doses to cardiac structures compared to free breathing in a supine position in patients with left-sided early-stage breast cancer?
Absolute Event Rate: 1.08% vs 1.92%
p-value: p=≤ 0.0001
Both prone free breathing and supine deep inspiration breath-hold significantly reduce radiation doses to the heart, left ventricle, and left anterior descending artery compared to supine free breathing during left-breast irradiation.
Supports cardiac-sparing positioning in breast radiotherapy; hypothesis-generating and requires prospective validation before practice change.
PURPOSE: To compare doses to organs at risk (OARs) for left-sided whole-breast radiation therapy with comparable planning target volume (PTV) coverage using three techniques: free breathing in a supine position (SFB), deep inspirational breath-hold in a supine position (SDIBH), and free breathing in prone position (PFB). MATERIALS AND METHODS: Thirty-three patients with left-sided early-stage breast cancer underwent CT simulation following SFB, SDIBH, and PFB protocols for whole-breast radiation therapy. One radiation oncologist contoured the breast PTV, heart, left ventricle (LV), and left anterior descending artery (LAD). Treatment plans were optimized using field-in-field technique with the AAA algorithm. Each plan was optimized to provide identical coverage to the PTV such that a reasonable comparison for OAR dosimetry could be evaluated. All plans were prescribed 42.56 Gy in 16 fractions to the left-breast PTV. RESULTS: The mean dose in SFB for the heart, LV, and LAD was 1.92, 3.19, and 21.73 Gy, respectively, which were significantly higher than the mean dose in SDIBH for the heart (1.08 Gy, P ≤ 0.0001), LV (1.50 Gy, P ≤ 0.0001), and LAD (6.3 Gy, P ≤ 0.0001) and in PFB for the heart (0.98 Gy, P ≤ 0.0001), LV (1.34 Gy, P ≤ 0.0001), and LAD (6.57 Gy, P ≤ 0.0001). Similar findings were noted for the cardiac components in SFB for V2.5, V5, V10, V20, and V30 compared with values in SDIBH and PFB. The mean dose for the left lung in PFB was 0.61 Gy that was significantly lower than in SFB (5.63 Gy, P ≤ 0.0001) and SDIBH (5.54 Gy, P ≤ 0.0001). Mean dose and dosimetric values for each OAR increased in SFB and SDIBH for patients with a large breast volume compared with values for patients with a small breast volume. CONCLUSIONS: SFB results in higher heart, LAD, and LV doses than the other techniques. Both PFB and SDIBH are more advantageous for these OARs irrespective of breast volume. PFB results in significantly lower lung doses than SFB and SDIBH. PFB always provided better results than SFB for the heart, LV, LAD, and lung. This conclusion contrasts with some published studies concluding that the prone position has no benefit for heart sparing.
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Saini et al. (2018) conducted an observational in left-sided early-stage breast cancer (n=33). Deep inspirational breath-hold in supine position (SDIBH) and free breathing in prone position (PFB) vs. Free breathing in a supine position (SFB) was evaluated on Mean dose to the heart (p=≤ 0.0001). Deep inspirational breath-hold (supine) and free breathing (prone) significantly reduced mean heart dose compared to free breathing in a supine position (1.08 Gy and 0.98 Gy vs 1.92 Gy; P≤0.0001).
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