Impact of radiation dose on complications among women with breast cancer who underwent breast reconstruction and post-mastectomy radiotherapy: A multi-institutional validation study

Seung Yeun Chung, Jee Suk Chang, Kyung Hwan Shin, Jin Ho Kim, Won Park, Haeyoung Kim, Kyubo Kim, Ik Jae Lee, Won Sup Yoon, Jihye Cha, Kyu-Chan Lee, Jin Hee Kim, Jin Hwa Choi, Sung-Ja Ahn, Boram Ha, Sun Young Lee, Dong Soo Lee, Jeongshim Lee, Sei One Shin, Sea-Won Lee, Jinhyun Choi, Mi Young Kim, Yeon Joo Kim, Jung Ho Im, Chang-Ok Suh, Yong Bae Kim

The Breast , [Online ahead of print], doi: 10.1016/j.breast.2021.01.003

ABSTRACT

Purpose: merging data suggest that higher radiation doses in post-mastectomy radiotherapy may be associated with an increased risk of reconstruction complications. This study aimed to validate previous findings regarding the impact of radiation dose on complications among women with breast cancer using a multi-center dataset.

Materials and Methods: Fifteen institutions participated, and women with breast cancer who received radiotherapy after either autologous or prosthetic breast reconstruction were included. The primary endpoint was major post-radiation therapy complications requiring re-operation for explantation, flap failure, or bleeding control.

Results: In total, 314 patients were included. Radiotherapy was performed using both conventional fractionation and hypofractionation in various schedules. The range of the radiation therapy dose in Equivalent Dose in 2 Gy fractions (EQD2; α/β = 3.5) varied from 43.4 to 71.0 Gy (median dose: 48.6 Gy). Boost radiation therapy was administered to 49 patients. Major post-radiation therapy complications were observed in 24 (7.6%) patients. In multivariate analysis, an increasing EQD2 per Gy (odds ratio [OR]: 1.58, 95% confidence interval [CI]: 1.26-1.98; p < 0.001), current smoking status (OR: 25.48, 95% CI: 1.56-415.65; p = 0.023), and prosthetic breast reconstruction (OR: 9.28, 95% CI: 1.84-46.70; p = 0.007) were independently associated with an increased risk of major complications.

Conclusions: A dose-response relationship between radiation dose and the risk of complications was validated in this multi-center dataset. In this context, we hypothesize that the use of hypofractionated radiotherapy (40 Gy in 15 fractions) may improve breast reconstruction outcomes. Our multi-center prospective observational study (NCT03523078) is underway to further validate this hypothesis.

- PMID: 33517043

- Fulltext: https://www.sciencedirect.com/science/article/pii/S0960977621000047?via%3Dihub