SP37. Fortification or Fibrosis? An Evaluation of Immune System Disorders and the Development of Capsular Contracture

Abstract

PURPOSE: Two-stage implant-based procedures remain the most common approach for women pursuing post-mastectomy reconstruction. Up to 20% of patients develop capsular contracture after surgery, which can lead to poor functional and aesthetic outcomes, cause significant discomfort, and require additional corrective procedures. While the etiology of capsular contracture has not been fully elucidated, most literature attribute the process to a pro-inflammatory response involving the innate immune system. Additionally, some have postulated that peri-operative bacterial colonization of the implant site may lead to fibrosis and contracture formation. Autoimmune disorders, which are linked to abnormal systemic inflammatory responses, and immunosuppression, which can increase susceptibility to a range of infections, are not uncommon in patients diagnosed with breast cancer. Thus, an understanding of the intersectionality between these conditions and post-operative complications could prove useful for surgical planning. The aim of this study is to evaluate the effects of autoimmune disorders and immunodeficiency on rates of capsular contracture among two-stage breast reconstruction patients. METHODS: A dataset consisting of 296 patients (520 samples) who had undergone two-stage breast reconstruction between 2009 - 2021 at a tertiary-care facility was used in the study. An array of patient data, such as demographics, past medical history, and social history were collected. The primary endpoint was contracture development, which was ascertained by reviewing the electronic health record. The secondary outcome of interest was time to contracture formation. The date of contracture development (t_c) is defined as the first mention of capsular contracture based on clinical assessment. The time to event is defined as t_c - t_implant if the subject developed contracture, t_c - t_present if the subject was contracture-free. Univariate logistic regression was used for statistical analysis. RESULTS: Among the cohort, 5% (26/520) and 10.6% (55/520) had concurrent immunosuppression and autoimmune disorders, respectively. The autoimmune disorders examined were rheumatologic and endocrine in origin. The immunosuppressed states included both viral (HIV, Hepatitis A/B/C) and oncological (multiple myeloma, monoclonal gammopathy of undetermined significance, chronic myelogenous leukemia) conditions. On univariate analysis, compared to patients without either conditions, autoimmune disorders (OR 1.15, p-value 0.64) and immunosuppression (OR 1.06, p-value 0.88) were not linked to significantly higher odds or earlier development of capsular contracture (p-value > 0.05). Further stratified analysis examining only patients with immune-based conditions did not reveal statistically significant differences in the timeline (OR 0.14, p-value 0.43) or odds (OR 1.07, p-value 0.878) of contracture formation between the subgroup with immune-overactivation and the subgroup with immunosuppression. CONCLUSION: Comorbid autoimmune disorders and immunosuppression do not appear to significantly affect the odds or timeline of capsular contracture development. When counseling post-mastectomy patients with similar past medical history, surgeons may safely offer the choice of implant-based procedures when presenting the various reconstruction modalities.