2792 - Spatial Analysis of Local Recurrence Patterns after Mastectomy and Reconstruction for Breast Cancer
Presenter(s)
W. Lui1, X. Wang2, S. Shao3, K. Jin2, X. Wang1, W. Shi1, J. Meng1, J. Luo1, X. Zhang1, X. Mei1, X. Chen4, J. Ma1, X. Guo5, Z. Yang1, L. Zhang3, and X. Yu1; 1Department of Radiation Oncology, Fudan University Shanghai Cancer Center; Department of Oncology, Shanghai Medical College, Fudan University; Shanghai Clinical Research Center for Radiation Oncology; Shanghai Key Laboratory of Radiation Oncology, Shanghai, China, 2Department of Radiation Oncology, Fudan University Shanghai Cancer Center; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China, 3Fudan University Shanghai Cancer Center, Shanghai, China, 4Department of Radiation Oncology,Fudan University Shanghai Cancer Center;Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China, 5Department of Radiation Oncology,Fudan University Shanghai Cancer Center; Department of Oncology, Shanghai Medical College, Fudan University, Shanghai, China
Purpose/Objective(s): To characterize the distribution of local recurrence (LR) in breast cancer patients following mastectomy and reconstruction, determining areas that are at high risk of harboring residual tumour deposits and providing anatomical guidance for clinical target volume (CTV) delineation.
Materials/Methods: Patients who developed LR following mastectomy and immediate reconstruction for primary breast cancer between 2007 and 2025 were identified, and were eligible for analysis if presenting with available computed tomography (CT), magnetic resonance (MR), positron emission tomography (PET)/CT or PET/MR images of LR lesion. The location of LR lesions were characterized based on anatomical layer and quadrant and compared with CTV defined by ESTRO consensus guideline for breast reconstruction setting (ESTRO-CTV).
Results: A total of 60 patients with 70 LR lesions were included. 49 patients (81.7%) presented with isolated LR and 53 patients (88.3%) developed solitary recurrent lesions. 64 in 70 lesions (91.4%) were located in subcutaneous tissues, whereas 5 lesions (7.1%) occurred in pectoralis major and one (1.4%) presented as skin recurrence. Among the 53 lesions in patients with subpectoral implant-based reconstruction (n = 45), 17 (32.1%) were located in upper inner quadrant (UIQ) and 11 (20.8%) in central quadrant (CQ). 45 lesions (84.9%) were in-ESTRO-CTV, 1 (1.9%) was marginal and 7 (13.2%) were out-of-ESTRO-CTV. Among the 13 lesions in patients with prepectoral implant-based reconstruction (n = 11; 5 with the additional use of latissimus dorsi flap), 4 (30.8%) were located in UIQ, 4 (30.8%) in upper outer quadrant (UOQ) and 2 (15.4%) in CQ. 11 lesions (84.6%) were in-ESTRO-CTV while 2 (15.4%) were marginal. No dorsal recurrence was observed in either subpectoral or prepectoral reconstruction. In the 4 patients who received autologous reconstruction, the most common site of recurrence was UIQ (50%). All 4 recurrent lesions were within a CTV that excluded autologous flap, resembling the ESTRO-CTV in the setting of prepectoral reconstruction. No recurrence was observed in the dorsal region of autologous flap.
Conclusion: This study provides a comprehensive spatial analysis of LR patterns after mastectomy and reconstruction for breast cancer. Findings suggest potential high risk of residual diseases in certain areas especially UIQ post-mastectomy in the setting of immediate breast reconstruction. The ESTRO-CTV offers substantial coverage for most recurrent lesions, supporting its clinical applicability. However, marginal and out-of-ESTRO-CTV recurrences highlight the need for individualized adjustments during CTV contouring according to tumour and treatment characteristics.