RPM Inspiration Gating: Improving Radiotherapy for Left Breast Cancer Patients with Anterior Heart Position.

BACKGROUND: Adjuvant radiotherapy for breast cancer reduces local recurrence and improves survival. In patients with left sided breast cancer, anterior heart position or medial tumor location may cause inadequate breast coverage due to heart shielding. Respiration gating using the Real-time Position Management (RPM) system enables pushing the heart away from the tangential fields during inspiration, thus optimizing the treatment plan. OBJECTIVES: To compare breathing inspiration gating (IG) techniques with free breathing (FB), focusing on breast coverage. METHODS: The study comprised 49 consecutive patients with left sided breast cancer who underwent lumpectomy and adjuvant radiation. RPM was chosen due to insufficient breast coverage caused by an anterior heart position or medial lumpectomy cavity. FB and IG computed tomography simulations were generated for each patient. Breast (PTVbreast) and lumpectomy cavity (CTVlump) were defined as the target areas. Optimized treatment plans were created for each scan. A dosimetric comparison was made for breast coverage and heart and lungs doses. RESULTS: PTVbreast V95% and mean dose (Dmean) were higher with IG vs. FB (82.36% vs. 78.88%, P = 0.002; 95.73% vs. 93.63%, P < 0.001, respectively). CTVlump V95% and Dmean were higher with IG (98.87% vs. 88.92%, P = 0.001; 99.14% vs. 96.73%, P = 0.003, respectively). The cardiac dose was lower with IG. The IG left lung Dmean was higher. No statistical difference was found for left lung V20. CONCLUSIONS: In patients with suboptimal treatment plans due to anterior heart position or medial lumpectomy cavity, RPM IG enabled better breast/tumor bed coverage and reduced cardiac doses.

Immediate breast reconstruction with anatomical implants following mastectomy: The radiation perspective.

Immediate implant-based breast reconstruction followed by postmastectomy radiation therapy (PMRT) is controversial because of the risk of compromised treatment plans and concerns regarding cosmetic outcomes. We evaluated the effects of immediate direct-to-implant breast reconstruction with anatomical implants on the quality of PMRT delivered by 3-dimensional conformal radiotherapy (3D-CRT). In this retrospective, single-institution study, patients who had undergone reconstruction with direct anatomic implant, performed by a single surgeon, received 3D-CRT between 2008 and 2013. For each patient, 2 plans (including or excluding internal mammary nodes [IMN]) were created and calculated. The primary end point was the dose distribution among reconstructed breasts, heart, lungs, and IMNs, and between right and left breasts. Of 29 consecutive patients, 11 received right-sided and 18 received left-sided PMRT to a total dose of 50Gy. For plans excluding IMN coverage, mean Dmean for right and left reconstructed breasts was 49.09Gy (98.2% of the prescribed dose) and 48.51Gy (97.0%), respectively. For plans including IMNs, mean Dmean was 49.15Gy (98.3%) for right and 48.46Gy (96.9%) for left reconstructed breasts; the mean IMN Dmean was 47.27Gy (right) and 47.89Gy (left). Heart Dmean was below 1.56Gy for all plans. Mean total lung volume receiving a dose of ≥ 20Gy was 13.80% to 19.47%. PMRT can be delivered effectively and safely by 3D-CRT after direct-to-implant breast reconstruction with anatomical implants, even if patients require IMN treatment.