ECC 2015

What are the obstacles in cancer prevention?

Prof Jack Cuzick - Queen Mary University of London, London, UK

You’re involved with a special edition on cancer prevention. What are the obstacles in cancer prevention, would you say?

This article very much focusses on preventive therapy, that is what you do for the high risk women. We now have a number of good options, starting with tamoxifen and raloxifene and also now the aromatase inhibitors which appear to be more effective. But it’s clear now that the biggest obstacles are not the scientific ones as to what to do but to actually educate doctors and patients about what the benefits are, who should actually be getting these treatments and how to minimise side effects.

Now that’s in breast cancer and you’ve talked about so-called chemoprevention, giving a drug to prevent breast cancer. What exactly is the principle of chemoprevention, how does it work?

Chemoprevention is very similar to what cardiologists have been doing for a long time. You find someone at increased risk, say higher blood pressure or high cholesterol. Cardiologists think nothing of reducing risk by giving drugs and this has been very effective in reducing heart disease. We’re trying to bring this idea into cancer. Now there are two major areas where I think there has been substantial success in understanding how to do this. One is in breast cancer where we have agents which basically are anti-hormone agents, tamoxifen, raloxifene and now the aromatase inhibitors, which reduce oestrogen levels and have a clear impact in terms of preventing cancer. More widely it’s just becoming clear very recently that actually aspirin, the wonder drug aspirin, actually has a substantial impact on cancer. In fact, if you do the sums, if you wanted to prevent cancer the most important thing is to not smoke but numerically the second most important thing to do is to take a baby aspirin. We estimate that probably we’ll reduce cancer incidence and mortality overall by about 10% in men and women.

Now, we’ve been hearing cautious information in gastrointestinal cancers today at the meeting in Vienna, here, about the use of aspirin. But there are obstacles to using it, what are they and what are the topics that you’re covering in this issue altogether?

One of the challenges is that when the only benefits of aspirin for the general population were cardiovascular benefits they were pretty much balanced by the gastrointestinal bleeding so that overall the risk benefit for the average person wasn’t great if you were just looking at the cardiovascular benefits. Over the last few years it has become very clear that the benefits on cancers is much larger than the cardiovascular benefit. It’s primarily colorectal cancer, stomach cancers and oesophageal cancer, but the benefits are about a 30% reduction in incidence of mortality for all three of those.

Are there any recommendations now, though, already?

There aren’t official recommendations. We’ve done a cost benefit analysis and come to the conclusion that for both men and women between the ages of 50 and 65 taking a baby aspirin, less than 100mg per day, for between five and ten years is going to be on average highly beneficial.

What then is the outlook for chemoprevention in the future and the outlook for preventing more cancers?

Chemoprevention, we like to call it preventive therapy now because chemoprevention, I think, is a little bit of the problem in the sense that it actually creates a sense that this is a toxic therapy like chemotherapy for cancer. In fact these agents, they do have some side effects but they’re really minimally toxic. We have to get that over to the public; we haven’t done a good job about educating both doctors and the public that cancer really is preventable by drug treatment in high risk cases, just like cardiovascular disease is. We really must do a better job in making that very, very clear that there are agents that can be taken which have a substantial impact on cancer.

What do you think is the outlook then?

I’m very optimistic, I must say. I think it’s a question of education. I’ve been involved with HPV and cervix cancer, we discovered the results more than twenty years ago, and people always ask me when is HPV going to be used as a screening test, I usually tell them 2005. We’re now in 2015 and that’s finally being introduced because the evidence is so overwhelming. I think the same thing will happen with cancer prevention using drugs. The data are really quite overwhelming now but we haven’t really made the strong case. There will be much more data coming out on aspirin over the next few years, people have to get comfortable with the idea that, just like heart disease, cancer can be prevented in high risk people by taking preventive therapy.