Goals/Purpose:
There is an ongoing debate about whether the periodic surveillance with magnetic resonance imaging (MRI), which is currently recommended by the FDA and in product labeling, should be advised for breast implant patients who are asymptomatic for rupture. In order to inform part of this conversation, a study with a large number of patients that underwent MRI was used to look at the frequency of implant removal in cases where patients were asymptomatic for rupture, yet had screened positive for rupture via MRI (“silent” rupture cases).
Methods/Technique:
A 10-year, prospective, open-label, multi-center clinical study of Mentor Contour Profile Gel (CPG) breast implants (manufactured by Mentor Worldwide LLC, Irving, Texas) is underway and data through 8 years are available. The study began in 2002 and includes 57 investigators, at 68 US sites, and 955 patients (572 primary augmentation, 124 revision-augmentation, 191 primary reconstruction, and 68 revision-reconstruction). The study consists of two MRI cohorts to screen for “silent” rupture: one with scheduled MRI scans at 1, 2, 4, 6, 8, and 10 years post-implantation (MRI Cohort A) and one with scheduled MRI scans at 8 and 10 years post-implantation (MRI Cohort B). An implant is considered to be ruptured if (1) the investigator reports an “overt” rupture, or (2) the most recent MRI evaluation indicates definite rupture or suspected rupture, unless (3) the implant has been explanted and then returned to, physically examined by, and determined not to be ruptured by Mentor. All explanted implants are to be returned to Mentor for physical examination per the study protocol, regardless of the reason for explantation.
Kaplan-Meier (KM) survival analyses of time to rupture were performed to estimate the cumulative incidence of rupture, and were based on follow up of patients through their last MRI exam. The KM method is specifically designed to take into account lost to follow-up (e.g., when a patient does not return for a study-specified visit or withdraws from the study), and follow up through the last MRI exam ensures that “silent” ruptures within the population are included. Only the original study implants were considered in the KM analyses.
Results/Complications:
MRI data through 8 years post-implantation were available for 49% (178 of 367 expected due) of MRI Cohort A patients and 44% (204 of 467 expected due) of MRI Cohort B patients. There were 26 rupture reports of original study implants in 24 patients - 11 reports among 11 patients in MRI Cohort A, and 15 reports among 13 patients in MRI Cohort B. The KM estimated rupture rates are presented in Table 1.
Table 1. Kaplan-Meier Cumulative Estimated Rupture Rates Through 8 Years.
In addition to the 26 reported ruptures among the 1831 original study implants, there were 3 reported ruptures in the 69 replacement study implants. Overall, of the total 29 reported ruptured implants, there were 4 symptomatic in 4 patients and 25 “silent” ruptures in 23 patients. A total of 15 of these 29 were confirmed after implant removal, and 14 remained as suspected rupture.
At the patient level, 52% (12 of 23) of the asymptomatic patients with a positive rupture signal by MRI decided not to have the implant(s) removed, and 48% (11 of 23) proceeded with implant removal (Figure 1). All 4 of the patients with symptomatic rupture had the implants removed.
Figure 1. Explantation in Cases of Asymptomatic (“Silent”) or Symptomatic Ruptures.
Conclusion:
Patients are advised by the FDA and in product labeling to undergo regular MRIs to screen for “silent” rupture even if the patient experiences no problems, and if rupture is noted the labeling instructs the physician to advise their patient to have the implant removed. Screening of all patients via MRI provides each patient with the opportunity to be informed of a “silent” rupture; however, how the patients and their surgeons decide to handle this information varies. The 8-year data from the Mentor CPG Core study shows two MRI cohorts with similar KM rupture rates, and suggests that approximately half of the patients decide not to have their implants removed if they have no apparent symptoms of rupture.