The wrong tools for the job?
点击量： 时间：2017-07-02 03:01:11
By Alison Motluk (Image: P. Marazzi/Science Photo Library) Gynaecologists have used power morcellators on hundreds of thousands of women for years. These devices are used to grind up tissue internally and suck it out through tiny incisions during keyhole surgery. Morcellators make it possible for a woman with a uterus the size of a basketball to have minimal scarring after its removal. These are mechanical devices not drugs. What could go wrong? Quite a bit apparently. Many candidates for hysterectomies have uterine growths called fibroids, and there are now suspicions that in as many as 1 case in 350 these growths are cancerous. And when you grind up a cancerous tumour inside the abdominal cavity, you risk seeding the disease elsewhere. That’s what happened last year to 40-year-old Amy Reed, at the time an anaesthetist at a Harvard-affiliated hospital. She and her husband, then a surgeon at another Harvard hospital, where she had the surgery, have spent the past 12 months fighting to have the devices banned. She had been told the odds of fibroid cancer were 1 in 10,000. In the last week of November, the US Food and Drug Administration (FDA) issued its long-awaited verdict. In the end, it did not ban morcellators. Instead manufacturers were told to include a prominent warning on their products, saying that they should not be used in women near to or post menopause, or in any woman suspected of having cancer – in other words, the majority of those who will have surgery to remove uterine fibroids. The following day, HCA Holdings, the largest for-profit hospital group in the US, said its facilities there would no longer use the devices. It has just banned them in its UK hospitals too. Though power morcellators are still in operating theatres, they will be used a great deal less frequently. This tale is the latest in a line of recent safety warnings about seemingly innocuous medical devices. There was the PIP breast implant scandal and the failure of metal replacement hips. All raise the question of whether approval systems are robust enough. The morcellator story has chiefly focused attention on the US system, but similar questions will be asked elsewhere. In the UK, new guidance on morcellators is imminent. Like many Americans, Reed and her husband, Hooman Noorchashm, believed that medical devices were carefully vetted. But when they started to look into how morcellators got on the market, and the kind of safety testing and follow-up that had been performed, what they discovered wasn’t comforting. The FDA has three categories for devices (not dissimilar to Europe), only one of which – Class III – requires evidence of safety before it can be sold. Those are things like implantable defibrillators and heart valves, and they are, as you’d expect, backed up with bench and animal science and clinical trials. They need pre-market approval. But many more devices only need pre-market notification. Known as “510(k) clearance”, after the clause in the US law that permits this, the process involves simply showing that there are already similar devices on the market, so-called “predicate devices”. All manufacturers need do is notify the FDA before starting to sell these products. Many class II devices, such as artificial hip and knee joints, pacemakers, most contact lenses – and morcellators – come into use this way. Take the morcellator that was used on Amy Reed, the Rotocut G1, made by Karl Storz Endoscopy. According to FDA documents, it was cleared on July 27, 2006. In giving it the go-ahead, the FDA wrote: “We … have determined the device is substantially equivalent … to legally marketed predicate devices marketed in interstate commerce prior to May 28, 1976 … or to devices that … do not require approval of a premarket approval application.” When asked, the FDA could not readily identify what the specific predicate device was, and told me I’d have to submit a freedom of information request, if I wanted to know. But it’s an interesting question. Given that the first power morcellators weren’t invented till the 1990s, using a predicate from before 1976 would be like arguing a sewing machine was “substantially equivalent” to a needle and thread. If its predicate is one of the first two power morcellators ever cleared for gynaecological use, it means the FDA has cleared dozens of devices used on hundreds of thousands of women based on testing in just 23 women. And that testing focused mainly on efficacy, not medium or long-term safety, demonstrating, for instance, the rate at which tissue was removed and the amount of blood loss. 510(k) clearance was supposed to be a temporary arrangement, but it has been in place for almost 40 years, and it doesn’t look likely to change anytime soon. About five years ago, the FDA asked an independent body, the Institute of Medicine (IOM), to look into whether the 510(k) process adequately protected patients and, if not, what would work better. The IOM committee’s conclusion was that 510 (k) did not provide protection, wasn’t designed to do so, and was so flawed that it should be scrapped. It pointed out that there is no premarket safety testing, relying instead on a “weak daisy chain of predicates”, according to David Challoner, a professor emeritus in health affairs at the University of Florida, Gainesville, and the man who chaired the IOM committee. The committee also highlighted the lack of mandatory post-market surveillance. After the report was published, there was pushback from industry, and nothing changed. Fear of reprisals, institutional inertia and just plain laziness has made individuals reluctant to report their concerns, but Challoner still believes post-market surveillance is the best hope. The FDA has already begun attaching unique identifier codes to devices, he says, which, in time, will be scanned into electronic patient records. That will give us the data to at least do skilled and impartial post-market surveillance. “Something like that would have picked up this morcellator issue much sooner,” he says. Alison Motluk is a science writer based in Toronto, Canada More on these topics: