Abstract P2-14-08: Immediate breast reconstruction with anatomical implants following mastectomy: The Radiation perspective

Abstract

Abstract Purpose: Immediate implant-based breast reconstruction followed by postmastectomy radiation therapy (PMRT) is controversial because of the risk of compromised treatment plans, particularly left-sided plans including internal mammary nodes (IMNs) as target. Using direct-to-implant reconstruction with anatomical implants may improve plans due to their unique shape over the chest wall. This single-institution study evaluated the effects of immediate breast reconstruction with anatomical implants on the quality of PMRT delivered by 3-dimensional conformal radiation therapy (3D-CRT). Methods and Materials: Patients undergoing immediate direct-to-implant reconstruction with anatomic implant, performed by a single surgeon, were treated between 2008 and 2013. For each patient, 2 plans were created and calculated, including or excluding IMNs. No electron fields were used. The primary endpoint was the dose distribution among reconstructed breast (RB), heart, lungs and IMNs and between right and left breasts. Six patients were treated with the Varian RPM system for left sided BC due to anterior heart position. Results: Of 29 consecutive patients, 11 received right-sided and 18 received left-sided PMRT. For plans excluding IMNs, mean Dmean was 49.09 Gy (98.2% of the prescribed dose) for right and 48.51 Gy (97.0%) for left RBs. For plans including IMNs, mean Dmean was 49.15 Gy (98.3%) for right and 48.46 Gy (96.9%) for left RBs. Mean RB D95 ranged from 42.05 Gy (left side with IMNs) to 45.15 Gy (right side with IMNs). Mean IMN Dmean was almost identical for left- and right-sided treatment (47.89 Gy and 47.27 Gy, respectively; P=.340). Heart doses were very low, with mean Dmean values of 1.25 Gy (range, 0.83-1.46) and 1.56 Gy (range, 1.23-2.10) for left-sided plans excluding and including IMNs, respectively (P<.001). Mean lung V20 values ranged from 13.80% for left-sided treatment excluding IMNs to 19.47% for right-sided treatment including IMNs. Conclusion: PMRT can be delivered effectively and safely by 3D-CRT after direct-to-implant breast reconstruction with anatomical implants. The reconstructed breast and the IM chain coverage were excellent and the heart dose was very low, (probably due to the use of the RPM system). Lungs V20 was comparable with other publication. Our study support the hypothesis that immediate breast reconstruction per se is not an impediment to the delivery of high-quality PMRT by modern 3D-CRT technology. Based on our findings, reconstructive surgeons should consider the use of anatomical implants for immediate breast reconstruction in patients requiring subsequent PMRT. Citation Format: Merav Akiva Ben-David, Hila Granot, Ilana Gelernter, Michael Scheflan. Immediate breast reconstruction with anatomical implants following mastectomy: The Radiation perspective [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P2-14-08.