Postmarket Study of Silimed’s Silicone Gel Polyurethane Foam–covered Breast Implants: Interim Results (2018–2024)

I read with interest the publication by Boechat et al1 describing the outcomes of a postmarket study on Silimed’s polyurethane (PU) foam–covered breast implants. The authors should be commended for their efforts in generating prospective clinical data on this surface technology, which has historically lacked robust long-term evaluation. The reported findings of patient satisfaction, low reoperation rates, and absence of capsular contracture (CC) or rupture are noteworthy. However, some methodological limitations raise concerns about the validity of the conclusions presented. First, the study was conducted at a single center, inherently restricting the generalizability of its findings. Second, although the authors present a 5-year follow-up, only 5 (1.46%) patients completed this timepoint, and only 35.09% met the 2-year follow-up time, which severely limits the capacity to assess long-term outcomes. These significant gaps in follow-up compliance were not addressed in the study’s limitations. It is understood that postmarket studies performed under strict regulations, such as those of the US Food and Drug Administration, must achieve a minimum follow-up rate of 60% at 10 years or provide a minimum of 80% follow-up rate at each timepoint per patient cohort,2 casting doubt on the reliability of the reported safety outcomes. Robust long-term surveillance is essential when assessing implant safety, as rupture rates tend to increase over time following repeated stress on the device.2 CC (grades III–IV) typically emerges after 1 year. Previous studies involving PU implants reported no occurrences of CC within the first 6 months. However, once the PU coating becomes macroscopically absent and degrades, typically at 3–4 years, CC rates increase sharply, peaking around year 8.3 Thus, the study’s limited sample of short-term observations is inadequate to declare reliability. Third, although the authors report 0 cases of rupture, it is unclear how many, if any, patients underwent magnetic resonance imaging screening for silent rupture. Although a planned imaging protocol is mentioned, adherence data are lacking, thereby limiting validation of the reported rupture rates. Fourth, the PU “velcro-like” adhesion may help stabilize the implant but can also trigger a significant inflammatory response. Previous comparative studies report that higher-roughness surfaces have shown significant foreign body reactions and capsule thickness compared to lower-roughness devices, particularly 4 μm.4 Despite this, the authors prematurely conclude that the PU surface poses a low risk of developing breast implant–associated anaplastic large cell lymphoma. This unsupported claim ignores global data, which report an increased incidence in individuals who received breast implants, with a median onset time of 8 years and a strong association with high surface roughness. PU implants have been linked to an estimated risk of 1 in 1800, surpassing the reported risk for Biocell implants (1 in 12,400), which were voluntarily withdrawn from all markets.5 In conclusion, this study holds particular value in a context where prospective data on PU implants remain scarce. The authors should be congratulated for their commitment to generating clinical evidence within a challenging regulatory and scientific landscape. Although this interim analysis provides promising early findings, definitive conclusions regarding the safety and efficacy of Silimed PU implants require further independent, controlled, and long-term studies. DISCLOSURE Dr. Munhoz serves as a consultant/board member for Establishment Labs Holdings, Inc., but has received no financial support in the preparation of this letter.