Immediate tissue expander or implant-based breast reconstruction does not compromise the oncologic delivery of post-mastectomy radiotherapy (PMRT).

Abstract

Increasingly, women are choosing immediate breast reconstruction (IBR) following mastectomy. Reports have indicated IBR may compromise post-mastectomy radiotherapy (PMRT). We investigated the impact of IBR on timing of PMRT, target coverage, and doses to organs at risk in a modern radiotherapy practice using advanced planning techniques. Between 2013 and 2015, PMRT was delivered to 116 patients (66 mastectomy alone, 50 IBR). PMRT was delivered with a median dose of 50Gy in 25 fractions. Left-sided patients were treated in breath-hold under image guidance. Differences in dosimetric parameters and time to the initiation of PMRT were assessed between patients with and without reconstruction. Reconstructed patients were younger and had lower clinical stage disease. Reconstruction did not significantly increase the mean time to PMRT initiation (51days reconstructed vs. 45days non-reconstructed, p=0.14) or the number of patients who initiated PMRT within 12weeks of the last therapeutic intervention (48/50 [96.0] vs. 61/66 [92.4%], p=0.41). There was no significant difference in the percentage of patients in whom the internal mammary lymph nodes (IMNs) were targeted (72 vs. 80%, p=0.29) or in IMN target coverage (mean IMN V40.5Gy 92.6 vs. 94.1%, p=0.62). Reconstruction did not significantly affect the mean ipsilateral lung V20 (25.4 vs. 26.4%, p=0.37) or the mean heart dose (2.2 vs. 2.1Gy, p=0.63). In a specialized breast multidisciplinary practice, immediate breast reconstruction did not significantly delay PMRT, compromise target coverage, or increase dose to organs at risk.