The answer is probably money, but more on that later.
I recently posted on the Lantus/cancer connection in my post A New Problem With Insulin: Cancer. The concern was triggered in a press release about a recent European report based on one earlier and three new studies which show a link between Lantus, a long acting insulin, and cancer. As I mentioned, I though it was interesting that more alarm has not been raised, particularly here in the US. Nissen's poorly done Avandia study got major press, and people stopped taking the drug (He was recently proven wrong- see here fore more info). Yet, for Lantus, the report is not about one study, but four studies that show similar findings that Lantus increases rates of cancer. In addition there are some biologically plausible reasons (more later) and a clear dose response. If you look at the criteria for causation, the Lantus/cancer connection seems to ring true. Yet, there seems to be not that much in the press and little public outcry to pull the medication from the market. This may be in part to the fact that the news cycle is now 24/7 Michael Jackson, but other medical stories, like the FDA and Tylenol, seem to be getting some attention, so this can't be the entire reason.
What do the experts say? The Europeans are making "an urgent call for more research". Yet, the US response is much more subdued. The official response from the American Diabetes Association (ADA) stated that findings from these research papers are conflicting and inconclusive, and cautioned against over-reaction until more information is available. A similar response can be found from The American Association Of Clinical Endocrinologists (AACE), the smaller but more academic group of diabetes specialists.
Where is the media attention on this? Where is the warning to patients? Why doesn't anyone seem to care?
MJ aside, here are some reasons:
1. The US experts don't want to say too much because of their ties to the drug companies. Both the ADA and AACE receive huge amounts of money from corporate sponsors, specifically the drug companies. In fact, back in 5/07 the experts issued a joint statement that had similar comments on the Avandia scare (which turned out to be correct). Sanofi-Aventis, the maker of Lantus, gives money to both of the ADA and AACE, and their members are unlikely to bite the hand that feeds them.
2. Though not all endocrinologists think alike, based on national and international diabetes recommendations, the expert guidelines recommend the use of insulin in type 2 diabetes much sooner than I would recommend. I have blogged in the past that I believe the endocrinologist making these recommendations may have a conflict of interest in that they have an incentive to make recommendations that will lead more patients toward insulin is because insulin use in type 2 diabetics is how they make their living. It is possible that the endocrinology experts are cautious about scaring the public about Lantus, because this may cause concern about all insulins, which they believe is the best treatment for diabetes.
3. The reason why Avandia drew more attention is because Dr. Nissen and some Congressmen were the ones making the noise, not the specialty societies. The Nissen meta-analysis on Avandia, from the data analyzed, to the publication, to the media frenzy had political motivations, whereas the Lantus studies do not. (See a timeline of the politics of the Avandia study in my post Diabetes Conspiracy )
Thanks to a comment on my previous post, I looked into the matter a little more. One of the problems with insulin is that is that it is related to insulin like growth factor (IGF-1) which has been shown to stimulate tumor growth. Regular human insulin has some affinity for the IGF-1 receptor, but Lantus has a much greater affinity, which is the likely reason more cancers were seen. There happens to be another long acting insulin on the market called Levemir that has very little affinity for the IGF-1 receptor (less than even human insulin) and is as effective as Lantus. In 2008, Lantus just missed the top 25 most commonly prescribed branded drugs at #26 with over 10.25 million prescriptions that year. Levemir came in at #170 with only 1.3 million prescriptions. Though I doubt this is public knowledge, I would guess that Novo Nordisk (the company that makes Levemir) is not giving nearly as much to these organizations as Sanofi Aventis (makers of Lantus), but I could be wrong. Since Levemir is a newer drug, is was not included in these studies and one can not rule out potential harm. That said, its low affinity for IGF-1 is reassuring. Thus, upon further reflection, I think that all diabetic patients who are on Lantus should talk to their doctor about insulin use, and if they need it, ask their doctor to consider switching them to Levemir.
Update: Via Med Page today, FDA just announced they were going to look into this. Not sure how much press this will garner. Certainly more valuable use of their time then trying to take down Tylenol.