Biomaterial-associated factors in silicone breast implant-related pathology

Silicone breast implants (SBIs) are among the most common surgically-implantable medical devices, but carry high complication rates, especially in the setting of post-oncologic breast reconstruction. These complications include capsular contracture, malposition, rupture, and breast implant-associated anaplastic large cell lymphoma. The development of SBI-associated complications is recognized to be multifactorial with the underlying mechanisms being poorly defined. Physical factors implicated in pathophysiology include gross mechanical stresses induced by the implant on surrounding tissue, the dissipation of friction stresses to local tissue by implant microtopography, and the incongruity of stiffness between local breast tissue, fibrous capsular tissue, and biomaterial, causing a significant gradient at the interface. Hypotheses of implicated chemical factors include direct adjuvant activity of the silicone material, the adsorption and persistence of pro-inflammatory factors at the interface, and the seeding of bacterial colonies. The current review explores in detail the physiology of the specific foreign body response to implanted materials associated with clinical SBIs, including the available evidence implicating both physical and chemical factors in the propagation of pathology. New advances in models and materials-based approaches to assessing and mitigating material-induced pathology are also reviewed. Finally, recommendations for SBI design, as well as further mechanistic work to address the pathophysiology underlying SBI-associated complications are outlined. STATEMENT OF SIGNIFICANCE: Treatment for breast cancer is associated with significant morbidity between surgical, radiotherapeutic, and systemic therapeutic approaches. Silicone breast reconstructive devices can allow for patients to regain confidence and personal efficacy after the trauma of cancer treatment. However, these devices are notorious for immune-mediated foreign body reactions, and patients can then suffer from painful or disfiguring fibrosis, and rarely a subtype of lymphoma or whole-body autoimmune reactions. Despite the ubiquity of these devices, the pathophysiological mechanisms underlying these complications are poorly understood. In this review, we review both clinical and fundamental approaches to understanding the development of pathology related to breast reconstructive devices, and discuss potential physicochemical approaches to device composition that may minimize these risks in the future.