BACR & ECMC: Therapeutic interventions for cancer prevention
Societal barriers to chemoprevention
Dr Andrea De Censi - E.O. Ospedali Galliera, Genova, Italy
Today I will be talking about the barriers to the implementation of prevention for cancer which is a real problem because we have very strong studies showing efficacy but the people don’t take these drugs. So I will be discussing a variety of reasons for this very low uptake and I think the most important which is the lack of business behind prevention because we are using very inexpensive drugs and all the medicine now is towards the use of very expensive compounds. All the resources are placed on treatment, drugs that prolong survival for a few weeks or months, but all the medical community is distracted by this commercial interest. So there are also very important ethical issues behind this tendency and little research, as you heard already, on aspirin, metformin, as well as other proven drugs like tamoxifen or raloxifene. So number one reason, I think, is the market – drug companies make more profit than any other industry in the world and 30% of these margins are due to the marketing which means also paying opinion leaders to spread these new drugs. Very little money is spared for prevention.
Of course there are many other reasons which have to do also with our tendency to remove the idea of dying, of being sick with cancer, so that people don’t like very much to think about when you’re healthy dying of cancer. Cancer is the incurable disease so the people don’t like very much to think about how to prevent cancer. It’s easier to prevent cardiovascular disease because the disease is not associated with such a bad prognosis. So the psychology of the human being is also something which is very important. If you’re aware of the concept of the risk you may paradoxically increase the avoidant attitude for those who are anxious or worried about cancer. So it’s very complex issues related to communication of risk, risk factors and risk reduction. The people like, perhaps, to hear about diet, exercise, but when you go to more difficult things like quit smoking or taking drugs then the issue is really becoming… the things become tough.
There are several other scientific reasons, perhaps more are related to the medical community. One is that the medical community doesn’t know very well their data in the literature on this cancer prevention reduction. There is an issue on the mortality reduction which is not being demonstrated yet because the follow-up is short and most of the data pertains to breast cancer which has a very good prognosis so we need maybe thirty to forty years to show an effect on mortality. Some people say, well, you see an effect on a reduction of incidence but not on a reduction of mortality which is perceived as a weak point. We did a survey among breast cancer specialists on which are the most important reasons for this low uptake and in addition to mortality there was the perception that the side effects may be an issue and drugs like tamoxifen have increased risk of endometrial cancer or vein thrombosis; aspirin has this effect on gastrointestinal bleeding. Other issues pertain to the regulatory aspects because if you give aspirin for cancer prevention you do an off-label prescription. So the doctor might be frightened to be sued if an adverse event occurs because you’re not protected by the indication. The labelling of the drug does not include cancer prevention. Likewise, tamoxifen is not indicated in Europe for cancer prevention, just in the US, Canada and recently in the UK.
So there are several reasons for this very low uptake. I am called to discuss strategies to overcome these barriers which is quite a difficult task but it is possible. I think the doctors must become more rigorous in terms of not being influenced by the commercial pressures of drug companies but this is against the stream, I realise. Perhaps one idea is to work with food supplements which are perceived as much more tolerable, non-toxic, and we are thinking of a cancer polypill which is a mixture of ingredients that resemble the Mediterranean diet but that are put in a way that your intake is measurable, is reproducible and in that way you can have a constant measurement to what you are taking for this. That’s one possible idea.
Where would you like to see cancer prevention brought into standard procedures?
I think, for instance, my category of medical oncologist is probably not the best one to prescribe drugs for cancer prevention. Actually one of the many barriers is it’s not clear who is the best doctor to prescribe these drugs, whether it’s a specialist in that organ. But there is some evidence now that working in the area of screening, for instance mammographic screening where the women attend the service and while they’re waiting for the mammography to be done you can measure their risk individually and then come back for counselling to discuss potential options if they have a higher risk like diet, physical activity or even medications. So that I see as a potential for increasing the uptake and awareness in subjects who are already sensitive to thinking about cancer because they attend the programmes of their national health system for mammography and Pap test and faecal blood test and so forth.
