1027 - Association of Blood Count-Derived Inflammatory Indices with Capsular Contracture After Post-Mastectomy Radiotherapy in Breast Cancer Patients Undergoing Direct-to-Implant Reconstruction
Presenter(s)
J. Y. Lee1, S. Y. Song2, D. W. Lee2, E. J. Yang2, J. Y. Kim3, J. Shin4, N. Kim5, J. S. Kim1, and J. Chang1; 1Department of Radiation Oncology, Yonsei Cancer Center, Heavy Ion Therapy Research Institute, Yonsei University College of Medicine, Seoul, Korea, Republic of (South), 2Department of Plastic and Reconstructive Surgery, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea, Republic of (South), 3Departments of Surgery, Yonsei Cancer Center, Yonsei University College of Medicine, Seoul, Korea, Republic of (South), 4National Cancer Institute/National Institutes of Health, Rockville, MD, 5Department of Radiation Oncology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea, Republic of (South)
Purpose/Objective(s): Direct-to-implant (DTI) breast reconstruction is widely used, but post-mastectomy radiotherapy (PMRT) substantially increases the risk of capsular contracture (CC). Blood count-derived inflammatory indices reflect systemic immune status and may be associated with fibrosis. We evaluated whether these indices could predict CC following DTI with PMRT.
Materials/Methods: We retrospectively analyzed 279 patients who underwent DTI, with or without PMRT, between 2019 and 2023. The primary endpoint was CC grade =2 (G2+ CC). We evaluated the association between PMRT and CC and whether this effect was modified by inflammatory markers. Multiple inflammatory indices (MLR, dNLR and others) were dichotomized using ROC-derived cut-offs, and interactions between PMRT and each marker were assessed using logistic regression. Among patients who received PMRT, subgroup analyses were performed to examine the association between CC, post-radiotherapy changes in inflammatory indices, and cumulative blood dose derived from a deep learning-based personalized dosimetry platform.
Results: PMRT increased G2+ CC risk. This effect was strongly modified by baseline inflammatory status, with high baseline MLR showing a markedly higher G2+ CC risk (59% vs. 3%), while baseline MLR had no association with G2+ CC in the absence of PMRT. PMRT remained an independent predictor of G2+ CC on multivariable analysis (OR 5.20, 95% CI 2.42-11.16), with a significant PMRT × MLR interaction (OR 8.86, 95% CI 1.00-78.28). Among patients who received PMRT, further subgroup analyses demonstrated that higher cumulative blood dose exposure (D5% =3.0 Gy) was associated with post-RT dNLR reduction (OR 2.8). Post-RT dNLR reduction was independently associated with an increased risk of G2+ CC (OR 3.00, 95% CI 1.46-6.16) and significantly improved model performance beyond baseline inflammatory markers. Grade 4 CC did not occur without PMRT (0/143); among PMRT recipients, rates were 0% in low MLR/stable–increased dNLR, 16.1% in low MLR/decreased dNLR, 6.9% in high MLR/stable–increased dNLR, and 26.5% in high MLR/decreased dNLR.
Conclusion: Baseline blood count-derived inflammatory indices and their post-RT changes were associated with CC risk after PMRT in DTI reconstruction. These findings are hypothesis-generating and require external validation and mechanistic studies incorporating detailed immune profiling.
| Endpoint | MLR Low / dNLR Stable-increase | MLR Low / dNLR Decrease | MLR High / dNLR Stable-increase | MLR High / dNLR Decrease | ?² p-value |
| Grade=2 | 33.3% (18.64–52.18) | 51.6% (34.84–68.03) | 37.9% (22.69–56.00) | 71.4% (57.59–82.15) | 0.004 |
| Grade=3 | 22.2% (10.61–40.76) | 41.9% (26.42–59.23) | 24.1% (12.22–42.11) | 55.1% (41.31–68.15) | 0.010 |
| Grade=4 | 0.0% (0.00–12.46) | 16.1% (7.09–32.63) | 6.9% (1.91–21.96) | 26.5% (16.21–40.26) | 0.009 |