The Incidence and Dosimetric Risk Factors of Capsular Contracture in Implant-Based Breast Reconstruction Following Post-Mastectomy Radiotherapy

Abstract Objective: In reconstructed breast cancer (RBC) patients, capsular contracture (CC) after radiotherapy (RT) can cause significant cosmetic issues and reduce quality of life. This study aimed to investigate CC incidence and associated risk factors at our center. Methods: Our retrospective study analyzed data from all RBC patients who received RT from June 2014 to January 2025. Chi-square and Fisher’s exact tests were used for categorical variables. Since continuous variables were not normally distributed, the Mann-Whitney U test (MWU) was employed. ROC analysis identified cutoff values for significant variables. Results: A total of 47 implants in 45 patients were analyzed. The median age was 42 (26-57), with a median follow-up of 41 months (5–95). Thirty patients (63.8%) received a permanent prosthesis; 17 (36.2%) had an expander then a prosthesis. Four patients (8.5%) were treated with boost and bolus in 10 (21.3%) cases. Capsular contracture occurred in 8 patients (17%), mainly within 18 months, with 62% being Baker grade 4. No significant relationship was found between CC and categorical variants (all p>0.05). The Dmean of the posterior implant edge (PMI) (p=0.005) and D2% dose (p=0.039) were significantly associated with CC. ROC analysis showed the PMI Dmean had the highest discriminative power (AUROC=0.817), with a cutoff of 5024.5 cGy (75% sensitivity, 94.9% specificity). The PMI D2% dose cutoff was 5265 cGy (62.5% sensitivity, 79.5% specificity). Conclusion: In this study, the PMI Dmean and D2% doses were found to be associated with CC. These findings should be validated in larger studies involving a greater number of patients.