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Elisabete Weiderpass, after her conference at the Spanish National Cancer Research Center (CNIO) / Laura M. Lombardía. CNIO
“Many women are unaware that even moderate alcohol consumption increases breast cancer risk”
“Drinking any amount of alcohol increases the risk of cancer. There is no safe amount”
“The increase in cancer cases we are seeing is definitely related to exposure to environmental carcinogens”
“For 60 years we have known that tobacco contains carcinogenic substances, and yet people still smoke"
Elisabete Weiderpass heads up the International Agency for Research on Cancer (IARC), whose reports are the basis of World Health Organization (WHO) recommendations. This researcher, who has given a lecture at the National Cancer Research Centre (CNIO), is a cancer epidemiologist, author of more than 700 scientific publications. Born in Brazil and based in Lyon (France), she has worked at the Karolinska Institute (Sweden) and the Arctic University (Norway), among other institutions.
Question. The importance of environmental factors in the development of cancer seems increasingly clear. Is that true?
Answer. What we know today is that between 40% and 50% of cancers can be prevented. Especially those related to smoking: about 20% of all cancers are directly linked to smoking. Alcohol is an important factor in about 5% of cancers, and diet that leads to obesity is also a major risk factor. Then there are other factors that contribute less but are still important, such as exposure to environmental carcinogens in the workplace, and radiation.
Q. With regard to alcohol, does moderate drinking also increase the risk?
A. Alcohol is a carcinogenic substance, end of story. The consumption of any amount of alcohol increases the risk of cancer. There is no safe amount. The risk curve is linear, the more you consume, the more your risk of cancer increases. The relationship between alcohol exposure and breast cancer risk is very interesting, evident in studies conducted in many European countries. Many women are unaware that it increases the risk of breast cancer, and that it is a preventable risk.
Q. What evidence is there that exposure to compounds used in industry, such as bisphenol A, increases the risk of cancer?
A. The French National Health and Safety Agency (ANSES) has published a study on Bisphenol A, and the conclusion is that it is associated with cancer, but also with reproductive problems, diabetes, and so on. This is the most important research we have on this compound. It has led to legislation already in place in France to limit the exposure of the population considered at risk, and to a more thorough control of this substance.
Q. Negotiations surrounding European regulations on the authorisation of chemical substances (REACH) pit environmentalists against the chemical industry. In your opinion, are European regulations adequate, or should they be tighter?
A. European regulations take into account not only scientific evidence but also economic consequences. There are many substances for which we have clear evidence that they are carcinogenic, but they are still on the market. That is a political decision, not a scientific one. As a scientist, I believe that scientific evidence should carry much more weight. But it is the politicians who decide what weighs the most in their decisions. For example, air pollution is a carcinogen. What is the permissible level of pollution in the different countries of the world? In China, permitted pollution levels are 400 times higher than in Europe. These are political decisions, not scientific ones.
Q. Should we be more demanding as citizens about such policies, even if they have an economic impact?
A. It is very important that citizens, and children in schools, have a better understanding of what scientific evidence is. Today there is so much contamination of information. In these matters, the opinion of an ordinary person is not as important as that of a scientist, if you want to have quality information. For 60 years now we have known that tobacco contains carcinogenic substances, yet people still smoke.
Q. WHO dietary recommendations are based on IARC reports on whether substances such as processed meat or alcohol are carcinogenic. How are these reports drawn up?
A. We review all the literature on molecular studies, in animal models, and humans, and with all that information we answer the question of whether or not a particular substance can cause cancer. But we do not evaluate the doses needed to cause it.
Q. Can you not tell us anything about the dose?
A. No. Returning to the example of atmospheric pollution, a mixture of chemicals and fine particles has the potential to cause cancer in humans. But the dose is assessed by individual countries, because they have to make the political and economic decision about it.
Q. But you did say that the higher the alcohol consumption, the greater the risk.
A. Yes, in general, when exposure to carcinogens increases, the risk increases.
Q. What does IARC say about meat consumption?
A. The assessments clearly show that it is carcinogenic, especially processed meat, meat that is mixed with different chemicals, such as salami, etc.
Q. Would the dietary recommendation be not to eat meat?
A. The IARC does not give recommendations. That’s not our function. We as a scientific organisation say that there is a risk in the consumption of meat; governments decide the recommendations for each country. WCRF (World Cancer Research Fund) assessments also conclude that the more meat you eat, the greater the risk of cancer, especially colon cancer.
Q. The increase in cancer cases is often attributed to population ageing. But to what extent does this increase have to do with environmental factors, such as pollution and an unhealthy lifestyle?
A. The combination of factors (tobacco, alcohol, poor diet, obesity, poor physical activity, chemical exposure, etc.) determines the risk of populations developing cancer, heart attacks, or cardiovascular episodes. There is also a stochastic process, meaning that cells are also likely to produce errors in their replication, which causes a person to develop a disease.
Q. So, the increase in cancer cases we are seeing is definitely related to exposure to environmental carcinogens
A. Definitely. Because genetics do not change, genetics are the same now as they were centuries ago. Very little has changed, what varies are the risk factors.
Q. But it is also true that we live longer now.
A. Indeed, when you live longer, errors in genetic replication have more time to occur the longer we live.