Monday May 13, on the set of C to you, Marie Toussaint, the leader of the Greens in the European elections, raised a cry of alarm: there would be, in France, more and more “clusters” of pediatric cancers, which would wipe out children who are usually spared from this disease. . The head of the list of Ecologists assured to see the effect of pollutants such as glyphosate or PFAS, or even GMOs, which it seeks to limit in the European Union.
A “mass poisoning”, really? The debate has resurfaced for years, to the great dismay of specialists on the subject, such as Véronique Minard-Colin, oncologist at Gustave-Roussy, the leading European center for research, teaching and care against cancer, and vice-president of the French Society for the Fight against Childhood and Adolescent Cancers and Leukemias (SFCE). Decryption.
L’Express: Marie Toussaint’s statements provoked the ire of scientists. Contrary to what is often believed, pollutants have modest or even innocuous effects on our health?
Véronique Minard-Colin: Of course, pollutants, like environmental factors, can be problematic, for various reasons. But, as a doctor and scientist, I must recall what we know, what has been documented by the most serious studies. And these works do not say what is regularly reported on the subject…
What do we know about the “clusters” mentioned by Marie Toussaint?
A cluster is a grouping of cases of the same pathology in time and space. There, we talk about pediatric cancers, but we often hear the term for infectious diseases, such as Covid-19. These cases are reported by the families of the sick, by caregivers, or by epidemiological registers.
When an aggregate seems significant, investigations are carried out to check whether it is simply a statistical chance or whether a new factor comes into play. As cancers in children are fortunately extremely rare, around 2,300 cases per year on throughout the territory, two young sick patients are enough in the same village for a suspicious report to be made.
How many clusters of childhood cancer are there in France?
To my knowledge, there are only two clusters of pediatric cancer cases considered abnormal currently in our country, one in Haut-Jura and one in Eure. A third, that of Sainte-Pazanne, in Loire-Atlantique, was recently excluded from the list after an investigation. It often happens that the term does not hold, for various geographical or statistical reasons. These clusters do not appear to be increasing.
These clusters of cases are certainly rare, but they remain no less worrying. How to explain them?
After a report, Public Health France dispatches teams to the site to analyze the soil, air and water. Independent researchers can also conduct investigations on their own. To date, no environmental product has been identified as the cause of the cancers identified. In reality, it is not clear why these clusters occur.
Work has also been carried out abroad on this subject, but, similarly, most of the time no cause is found. The clusters go out, then reappear in other places. Such behavior suggests that there is no single environmental factor, such as pesticide pollution, because otherwise the aggregations would be persistent and increasingly significant.
The environment doesn’t come into play at all?
It is always possible that the environment and pollutants have their share of responsibility, in certain cases. Simply, to date, the data from epidemiological surveys do not allow us to confirm this.
What is usually involved in the occurrence of these tumors, at least the most common ones?
A genetic factor is identified in 10 to 15% of cases. For the rest, research is underway. On genes mutated in mosaics for example. These are different genetic codes that we sometimes have in certain cells. On the immune system too. During the first years of life, he is more immature and more tolerant. This helps prevent it from confronting the mother’s cancer during pregnancy, but it could also have an effect on how the body monitors the cancer.
Work is also being carried out on cell division. At this age, it is very important. More divisions mean more “copies” of cells and therefore more risk of errors. It’s a hypothesis. Finally, there are of course studies on environmental factors, which are not only carried out on clusters, but on all pediatric cancers.
In the United States, certain teams have focused on vaccines, or on visiting farms, for example. In reality, these two elements seem rather protective, probably by “education” of the immune system. However, an increased risk was highlighted among children living near certain roads. But these results are still debated and the effect is very weak. All this again points to a combination of factors. Otherwise, we would have already found it.
You do not mention the most common causes in adults, such as alcohol or tobacco…
Many colleagues have looked at the main causes in adults: alcohol, tobacco, sun, obesity. This was done in France as part of the ESTELLE and ESCALE projects. In reality, these causes do not really weigh in the balance. Which is not surprising, because we do not find the same cancers in children as in adults. There is almost no lung, breast or skin cancer, but rather leukemia or lymphoma, brain tumors, etc.
No clear causes, multiple avenues… Why are these cancers so mysterious?
Pediatric cancer is very special. First, because it is rare, which complicates research. Each case is almost unique. This is why the French Society for the Fight against Childhood and Adolescent Cancers [SFCE] and the Inca [l’Institut national du cancer] are participating in the “G7 cancer”, a coalition of seven countries who will share their data, in order to compile them, in the hope that this can help science. Then, because these diseases occur at very early stages of life, whereas cancer is normally a long-term disease. Which apparently involves completely different mechanisms.
There is a research consortium in France called PEDIAC, bringing together eleven of the best scientific teams on the subject. This work should help advance science on the origin and causes of pediatric cancers. Let us continue our efforts: once these mysteries are resolved, the chances will be greater of finding suitable therapies and screenings.
Why do you think there is so much misinformation on this topic?
This is a particularly sensitive subject, a real cataclysm for families. Each case is a tragedy that we must avoid. The first question parents ask me is “why”. Why my child? It’s heartbreaking not to be able to answer. I understand that we are looking for explanations at all costs, even if it means picking and choosing among non-scientific communications. They are unfortunately very numerous.
You also say that there is no epidemic of cancer among children, as we regularly hear. How can we be sure of this, when the Inca, the body responsible for the subject, does not publish statistics for people under 40?
I assure you that we take each case very seriously. If the Inca does not publish statistics, that does not mean that there is no monitoring. We have a register which covers the entire territory and lists all cancers up to 18 years old. It is run by scientists and compiles numerous sources, such as the Cnam, hospitals and investigators’ reports. They assist the staff and are present alongside us. There are two in Gustave-Roussy alone, in my department.
What the data that comes out of this shows is that there is not a massive increase in cases. In reality the trend has been very stable for decades, in France and other industrialized countries. It is also very closely monitored: I don’t think we can say, as is often said, that the State is burying its head in the sand. In any case, personally, I have no such hindrance in my research.
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