Are PIP breast implants safe?
In all the furore about the banned PIP breast implants, one question remains unanswered: are they safe?
The Commons Health Select Committee talks of a striking "absence of evidence" over safety issues.
In January an expert group headed by Sir Bruce Keogh confirmed categorically that there was no higher cancer risk from PIP implants compared to other devices.
But the committee did not have enough evidence to rule conclusively on the PIP rupture rate compared to other implants, nor whether they were more difficult to remove than other devices following a rupture.
The French authorities did report both higher rupture rates and spoke of the risks of inflammation in the surrounding tissue.
MPs on the Health Committee say the absence of evidence meant the policy response became one of judgement and caution rather than scientific imperative. This explains why the French have advised routine removal of all PIP implants and the British have not.
The French - and Germans - argue that this is a sensible precaution because of the long-term doubts over the safety of the implants and the lack of knowledge about the composition of the gel filler that was used.
Toxicological tests on the PIP filler material have so far not yielded any clear concerns about the filler compared with other silicone implants. So the advice here is that routine removal is not advisable.
The Health Committee is critical of the MHRA and the Department of Health for not doing more on this issue between March 2010 and December 2011.
The earlier date was when the implants were banned. The MHRA put out a fairly bland press notice on 31 March 2010 and the issue attracted some publicity over the coming months, but not a great deal.
In September 2010 the MHRA released what it called "encouraging" results of UK testing of PIP implants which found no evidence of cancer risk nor of chemical toxicity.
The Commons Health Committee says a high-profile response should have been adopted here sooner and criticises the action taken after March 2010 as inadequate. In particular the MPs say private clinics had a duty to contact patients directly and the MHRA and Department of Health should have raised public awareness.
It was not until December 2011, when the French authorities recommended all women there have the implants removed, that the issue exploded across the media.
So where does this leave women who have PIP implants?
What they need is certainty as to whether the devices inside them pose any significant health risk, and at present Sir Bruce Keogh's Expert Group says there is no solid evidence of that.
The Health Committee says that "some further evidence has been emerging about the inflammatory properties of the PIP implants whether ruptured or not" and this should be examined urgently.
It concludes that if the surgery to take out ruptured PIP implants involves "significant complications", then this would be an argument for recommending early removal.
It is worth bearing in mind that every implant has a finite life-span - the figure of 10 years is a crude estimate - and many women may be biding their time about when they choose to have surgery.
The Health Committee said the refusal of the NHS in England to allow women to pay for new implants during surgery to remove the PIP devices was deterring some from taking action.
Latest figures from the Department of Health reveal that more than 5,000 private PIP patients have been referred for a specialist NHS consultation, and more than 3,000 have been scanned.
About one in five women going through the NHS route have decided to have the implants removed. What is not clear is the proportion who decide to seek private treatment to replace implants and the numbers choosing to take no further action.
All, I'm sure, would welcome definitive health guidance from the expert group as soon as possible.