Cancer chemo-prevention – S.A.M. strategy: Statins, Aspirin, Metformin
Cancer prevention by medications has strong but at times controversial evidence. What does eminent cancer expert think of aspirin, statins and metformin to reduce risks of cancer?
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– Chemoprevention of cancer. There is a so-called S.A.M. strategy: Statins, Aspirin, Metformin. I discussed chemoprevention with several prominent cancer experts, including prostate cancer experts. For example, with Jack Cusick in London, who called Aspirin “#2 most important step after not smoking in cancer prevention” – Yes What is your view on using pharmaceuticals in preventing or reducing risks of cancer, maybe Metformin, Aspirin? Possibly statins – they have a very different track record, but nevertheless there is some data [on statins] What is your view on pharmaceuticals in cancer reduction and prevention? I have several different thoughts about that. Sure, Aspirin is clearly an important drug not only for cardiovascular prevention, but also for colon cancer and probably other tumors. There’s evidence that aspirin intake reduces the incidence of other kinds of cancer, although I think the most impressive data is for colon cancer. Metformin is very interesting drug – it lowers insulin levels. And we know that insulin is implicated in causing – not causing – but accelerating the growth of cancers. So it is very possible that Metformin use could lead to reduced incidence of clinical cancers. I don’t think it will prevent cancers, but I think it could potentially slow the growth of cancers. I am less familiar with statins. I know the data is sort of mixed there. Some people have done studies, which indicate lower incidence of GI cancers, colon cancers, others have not found that to be true. I think the story is still out, so I’m not convinced that we need to take statins for that reason. Obviously statins help with heart disease and they’re also anti-inflammatory – they reduce inflammation. And we know inflammation can accelerate cancer too. So there’s rationale there. But it isn’t clear that people that take statins will actually prevent a significant number of cancers. I think one of the problems with cancer prevention and pharmacologic interventions – drugs used to treat cancer – is that all drugs have side effects. So you have to look at the balance between how much good is done, how much benefit there is, and how much risk is involved. So for aspirin, for example, there’s an increased incidence of stroke and GI bleeding, and CNS [brain] bleeds. So there’s always this balance between benefit and risk. It has to be taken into account. The same thing with statins. There are some people that develop very serious liver injury and muscle injury just taking normal doses of statins. So it’s not without some risk. And so you have to really look at whether the data is very solid and actually proves that statins are useful. But I think in general it’s a very promising field. It takes a long time to do these studies, many of these studies. The endpoint is actually improving patient survival – that’s a multi-year process. So it’s not easy to actually show that you’ve done some good. And it’s also interesting that, for example, in Aspirin the risk for GI bleeding is also correlated with H. pylori infection – that many people don’t know about it. So by screening for H. pylori you can actually reduce the risk of gastrointestinal bleeding. It’s a treatable infection. Yes, yes, certainly the presence of ulcers is certainly a risk factor. – You’re right. So in certain patients and subpopulations [medications for cancer prevention] may be very effective, and in others it could be dangerous. People may have a family history of amyloid degeneration in the brain. For example, in my own family, my mother had several strokes of this kind. And this puts people at increased risk of GI bleed or of CNS [brain] bleeding, and that would be another factor to take into consideration. Again, careful selection of patients, not a cookie- cutter approach – not “everything for everyone” – but selecting a personalized medicine. – Yes, personalizing it to a certain extent. – For statins, some of the clinical trials are interpreted that it is the low dose of statins that is active enough on the vascular endothelial wall – Yeah – that might be responsible for significant positive anti-tumor effect. – Yeah, that’s true! Or it could be the anti-inflammatory effect of statins that’s important. – [AT] And low doses… – Yes, the doses are important. So for aspirin – it’s a quarter of a usual dose that’s effective for preventing cancers. So I think one of the important points to make is that in the future we may be able to personalize this by testing the genetics. So for tumors that are inherited for a variety of reasons, such as breast cancer or colon cancer, it may be possible to pick out the susceptible population and target your prevention to those people. That is a very important point, as genetic tests are reduced in price, and their availability increases. But also careful selection based on the family history. – Right! Exactly, exactly…