Cancer prevention by medications has strong but controversial evidence. What does eminent cancer expert think of aspirin, statins and metformin to reduce risks of cancer? Chemoprevention of cancer. There is a so-called S.A.M. strategy. Statins, Aspirin, Metformin. Dr. Anton Titov, MD. I discussed chemoprevention with several prominent cancer experts. It included prostate cancer experts. For example, Jack Cusick in London 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? Cancer prevention by statins, possibly? Dr. Anton Titov, MD. Statins have a very different track record. But nevertheless there is some data on statins against cancer. What is your view on pharmaceuticals in cancer reduction and prevention? I have several different thoughts about that. Dr. Bruce Chabner, MD. Sure, Aspirin is clearly an important cancer medication not only for cardiovascular prevention, but also for colon cancer. Aspirin might prevent 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 cancer medication. It lowers insulin levels. We know that insulin is implicated in 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. Dr. Bruce Chabner, MD. But I think metformin could potentially slow the growth of cancers. I am less familiar with statins. I know the data is sort of mixed on statins against cancer. Some cancer patients have done clinical trials with statins. This 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 to prevent cancer. Obviously statins help with heart disease. Statins are also anti-inflammatory. They reduce inflammation. Dr. Bruce Chabner, MD. We know inflammation can accelerate cancer too. So there's rationale there to use statins. But it isn't clear that patients that take statins will actually prevent a significant number of cancers. Dr. Anton Titov, MD. I think one of the problems with cancer prevention and pharmacologic interventions is that all cancer medications have side effects. The cancer medications that are used to treat cancer. So you have to look at the balance between how much good is done. How much benefit is there. And how much risk is involved. So for aspirin, for example, there's an increased incidence of stroke and gastrointestinal bleeding, and 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 patients that develop very serious liver injury and muscle injury just taking normal doses of statins. So it's not without some risk. Dr. Bruce Chabner, MD. So you have to really look at the data. Data has to be very strong. It 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 clinical trials. We do many of these clinical trials. The endpoint is actually improving patient survival from cancer. That's a multi-year process. So it's not easy to actually show that you've done some good. Dr. Anton Titov, MD. It's also interesting that in Aspirin the risk for gastrointestinal bleeding is also correlated with H. pylori infection. Many patients 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 correct. So in certain patients cancer medications for cancer prevention may be very effective. In others cancer prevention cancer medications could be dangerous. Dr. Bruce Chabner, MD. 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. This puts patients at increased risk of stomach bleed or brain bleeding. That would be another factor to take into consideration. Again, careful selection of patients. It is not a cookie-cutter approach. Cancer prevention is not "everything for everyone”. Dr. Anton Titov, MD. We have to select a personalized medicine. Yes, personalizing cancer prevention 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. Yes. 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. Yes, the doses are important. So for aspirin it's a quarter of a usual dose. That's effective for preventing cancers. Dr. Bruce Chabner, MD. So I think one of the important points to make is that in the future we may be able to personalize cancer prevention dose of cancer medications. We have to test the genetics. So for tumors that are inherited for a variety of reasons we test genetics. Breast cancer or colon cancer have genetic influence. It may be possible to pick out the susceptible population. Dr. Anton Titov, MD. You can target your prevention cancer medications to those patients. That is a very important point. Genetic tests are reduced in price. Their availability increases. But also you need a careful selection based on the family history of cancer. Dr. Bruce Chabner, MD. Correct! Exactly, exactly.