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Abstract
The European Society for Radiotherapy and Oncology-Advisory Committee in Radiation Oncology Practice (ESTRO-ACROP) updated a new target volume delineation guideline for postmastectomy radiotherapy (PMRT) after implant-based reconstruction. This study aimed to evaluate the impact on breast complications with the new guideline compared to the conventional guidelines. In total, 308 patients who underwent PMRT after tissue expander or permanent implant insertion from 2016 to 2021 were included; 184 received PMRT by the new ESTRO-ACROP target delineation (ESTRO-T), and 124 by conventional target delineation (CONV-T). The endpoints were major breast complications (infection, necrosis, dehiscence, capsular contracture, animation deformity, and rupture) requiring re-operation or re-hospitalization and any grade ≥2 breast complications. With a median follow-up of 36.4 months, the cumulative incidence rates of major breast complications at 1, 2, and 3 years were 6.6%, 10.3%, and 12.6% in the ESTRO-T group, and 9.7%, 15.4%, and 16.3% in the CONV-T group; it did not show a significant difference between the groups (p = 0.56). In multivariable analyses, target delineation is not associated with the major complications (sHR = 0.87; p = 0.77). There was no significant difference in any breast complications (3-year incidence, 18.9% vs. 23.3%, respectively; p = 0.56). Symptomatic RT-induced pneumonitis was developed in six (3.2%) and three (2.4%) patients, respectively. One local recurrence occurred in the ESTRO-T group, which was within the ESTRO-target volume. The new ESTRO-ACROP target volume guideline did not demonstrate significant differences in major or any breast complications, although it showed a tendency of reduced complication risks. As the dosimetric benefits of normal organs and comparable oncologic outcomes have been reported, further analyses with long-term follow-up are necessary to evaluate whether it could be connected to better clinical outcomes.

Affiliations

Jung Bin Park 1 2, Bum-Sup Jang 1 2, Ji Hyun Chang 1 2, Jin Ho Kim 1 2, Chang Heon Choi 1, Ki Young Hong 3, Ung Sik Jin 3, Hak Chang 3, Yujin Myung 4, Jae Hoon Jeong 4, Chan Yeong Heo 4, In Ah Kim 5, Kyung Hwan Shin 1 2 6
1Department of Radiation Oncology, Seoul National University Hospital, Seoul, Republic of Korea.
2Department of Radiation Oncology, Seoul National University College of Medicine, Seoul, Republic of Korea.
3Department of Plastic and Reconstructive Surgery, Seoul National University Hospital, Seoul, Republic of Korea.
4Department of Plastic and Reconstructive Surgery, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
5Department of Radiation Oncology, Seoul National University Bundang Hospital, Seongnam, Republic of Korea.
6Cancer Research Institute, Seoul National University College of Medicine, Seoul, Republic of Korea.
PMID: 38846971