The UK’s regulatory authority the MHRA has issued an updated summary of the toxicology study performed on PIP implants earlier this year. The data confirms the earlier findings, stating that the PIP implants showed detectable differences in rupture rate within five years, and while reactions were noted in some patients, there was no concern expressed about so-called “silent ruptures”, given that by definition they have not provoked such a reaction.
The full report is pretty self explanatory and can be found here. In essence, at the end of June 2010, AFSSAPS (French regulatory body) told the MHRA of delays to their product testing, subsequent to which MHRA, symapthetic to the concerns of implanted women, decided to commission some limited testing to obtain an early indication of genotoxicity.
In July 2010, the MHRA agreed with the relevant experts on the Committee on the Safety of Devices to commission one specific series of tests on PIP silicone. These were Ames tests that measure the genotoxic activity of chemicals, which is linked with an ability to cause cancer. It was considered that these would give some important information on whether there were potential health risks associated with the filler material. These tests were uniformly negative.
Subsequently, in early January 2012, when the furore was at its peak, MHRA collated and presented implant rupture data to an expert group which concluded that there remained a shortfall in data required to make an informed decision, so requested further data collection.
Part of what it demanded was further toxicological testing to establish whether the industrial grade silicone used in the implants could be definitively shown to not cause harmful effects. Although a final report was issued in June, the work is still ongoing, but to date no toxicological effect has been elucidated.
Back to the real world data on implant rupture, the expert group requested further data from implanting centres to include the total number of women who received implants each year over the period 2001-2011, the reasons for explantation, and the clinical findings at explantation, of all explantations carried out over the same period and the reasons for explantation and the detailed clinical findings at explantation for all PIP breast implants removed from February to May 2012.
The resulting data on some 240,000 implants given to 130,000 women included detailed findings from 5,600 explant operations. The main findings from this analysis confirm what we’d already heard, namely that PIP implants are more likely to fail than other implants, by a factor of around 2-6, and the divergence between PIP and other implants is already apparent after five years.
Furthermore the reported data suggest a failure rate for PIP implants of 1.2% at 5 years, rising to 3.1% at 10 years. This compares with a failure rate for other brands of silicone gel implant of 0.2 – 0.4% at 5 years and 0.5 – 1.1% at 10 years.
However the true underlying failure rate, including ‘silent’ ruptures, will be greater than this.
PIP implants are more likely than other implants, by a factor of around 3-5, to result in local clinical signs. The rate of explants with local clinical signs is 0.8% at 5 years rising to 2.1% at 10 years . In absolute terms, these complication rates appear quite low although again the true underlying rates may be rather higher.
Again, based on the data, and correlating with toxiclogy studies, PIP implants do not seem to be associated with higher risks of other clinical problems such as capsular contraction, haematoma or cancer.