Breast Implant-Associated Conditions: Exploring the Potential Role of Chronic Inflammation and the Host–Implant–Microbiome Interface

Background/Objectives: Breast implants are widely used in aesthetic and reconstructive surgery. Although they are not associated with an increased risk of breast carcinoma, growing attention has focused on implant-associated conditions, including breast implant-associated malignancies, breast implant illness (BII), and autoimmune or inflammatory manifestations. This review examines current evidence and explores the potential role of chronic inflammation and the host–implant–microbiome interface in these conditions. Methods: A narrative review was conducted focusing on implant-associated malignancies, BII, autoimmune manifestations, chronic inflammation, implant-associated biofilms, and host–implant interactions. Evidence from oncology, immunology, microbiology, and biomaterials research was integrated to evaluate potential mechanisms underlying implant-associated local and systemic manifestations. Results: Recent evidence suggests that prolonged host–implant interactions, persistent foreign body responses, implant-associated biofilms, microbial persistence, and chronic immune stimulation may contribute to long-term alterations within the peri-implant environment. These mechanisms have been proposed as potential contributors to breast implant-associated malignancies, as well as to systemic manifestations such as BII and autoimmune or inflammatory conditions. Although BII and autoimmune/inflammatory syndrome induced by adjuvants (ASIA) have received increasing attention, causal relationships with breast implants remain unproven, and available evidence is limited by methodological heterogeneity, lack of standardized diagnostic criteria, and potential confounding factors. Conclusions: Emerging evidence highlights a complex interplay among implanted biomaterials, microbial biofilms, and host immune responses. The host–implant–microbiome interface may promote a biological environment that promotes persistent immune stimulation and chronic low-grade inflammation, providing a biologically plausible framework for interpreting heterogeneous implant-associated conditions. Further studies are needed to clarify the role of host–implant–microbiome interactions in implant-associated local and systemic manifestations.