2653 - Exploration of Flap-Protected Hypofractionated Radiotherapy in Patients with Locally Advanced Autologous Reconstructive Breast Cancer

M. Abulimiti¹, X. Li², X. Tie², X. Su³, W. Zhang⁴, L. Feng⁴, X. Xiang⁵, Y. Tan¹, Y. Yang⁶, G. JiDong⁷, and J. Jin⁸; ¹Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, China, Shenzhen, China, ²Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, China, ShenZhen, GuangDong, China, ³Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, shenzhen, China, ⁴Department of Radiation Oncology, National Cancer Center / National Clinical Research Center for Cancer / Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, China, ⁵Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, China, Shenzhen, GuangDong, China, ⁶Department of Radiation Oncology , National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital and Shenzhen Hospital, Chinese Academy of Medical Sciences & Peking Union Medical College, Shenzhen, China, ⁷National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, ShenZhen, GuangDong, China, ⁸?Department of Radiation Oncology, National Cancer Center/National Clinical Research Center for Cancer/Cancer Hospital & Shenzhen Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, China, Shenzhen, China

Purpose/Objective(s): Objective
Postmastectomy irradiation often negatively impacts breast reconstruction outcomes. This study aimed to (1) explore the feasibility of a target area outlining approach with flap protection. (2) accurately assess the impact of hypofractionated radiotherapy on autologous breast reconstruction.

Materials/

Methods:

Data was collected from 69 patients who underwent deep inferior epigastric perforator (DIEP) reconstruction from January 2021 to January 2024. Median age of 32 (31 to 63). Patients were divided into two groups: 38 cases in the hypofractionated radiotherapy(HFRT)group, 30 cases in the control group who did not requiring radiotherapy. For radiotherapy, the CTVcw is defined as the CTV minus FV-5mm, resulting in a doughnut-like or volcano-like area that includes the chest wall and skin. All were treated with volumetric modulated arc radiotherapy(VMAT)radiotherapy. A total of 43.5Gy/15f was prescribed to the CTV. Statistics Dmean Fv-5mm, V30,V35,V40, and D43.5Gy. Evaluated postoperative complications using Kwok grading. One month and every three months after the treatment, The doctors scored the patients Kroll score according to four aspects: symmetry, scaring, shape, and proptosis. At the same time, patients completed the BREAST Q 2.0 questionnaire. Compared Kroll scores by t-test in both group. A total of 303 Kroll scores and 46 BREAST Q scales were collected.


Results:

1. The dose of radiotherapy in 38 patients was statistically calculated with Dmean(FV-5mm)=41.7Gy, V30=98.6%, V35=96.6%, V40=88.5%, D43.5Gy(FV-5mm) =62.6%. A total of 7 (7.4%) patients had postoperative complications, including 1 case of Kwok grade 2 necrosis (5-15% necrosis). 6 cases of grade 1 necrosis (<5% necrosis), of which five patients with (P=0.34).
2. Median follow-up was 15 months (1-37 months) The Kroll score was higher in the radiotherapy group than in the no-radiotherapy group (1 score for Excellent, 2 for Good, 3 for Moderate, 4 for Poor), with statistically significant differences in cosmetic outcome at one month, three months, and 6 months postoperatively. (p=0.006, p=0.002, p=0.01 respectively) . There was no statistically significant difference in the cosmetic outcome from 9 months to 2 years postoperatively. (P>0.05).
3. Breast Q satisfaction scores showed a minimum satisfaction of 51.4 (45-56) one month after radiotherapy. All aspects of satisfaction increased over time, with a total satisfaction score of 67.8(54-80)two years after radiotherapy, with the most significant increase in satisfaction being mental health satisfaction.

Conclusion:

1. Flaps-protected target-area outlining of doughnut-like or volcano-like with VMAT radiotherapy can effectively reduce the prescribed dose of the flap.
2. Hypofractionated radiotherapy for autologous flap reconstruction of breast cancer has the same cosmetic outcome as patients without radiotherapy from 6 months after radiotherapy.
3. Reconstruction-related quality of life gradually improved with the end of treatment.